diff --git a/Codeforces/#671 (Div. 2)/A.cpp b/Codeforces/#671 (Div. 2)/A.cpp
new file mode 100644
index 0000000..5aba33d
--- /dev/null
+++ b/Codeforces/#671 (Div. 2)/A.cpp	
@@ -0,0 +1,118 @@
+/*
+	author: blair_
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+typedef long long ll;
+
+template <typename Arg1>
+void prn(bool space, Arg1&& arg1)
+{ cout<<arg1; if(space) cout<<" "; else cout<<"\n"; }
+template <typename Arg1, typename... Args>
+void prn(bool space, Arg1&& arg1, Args&&... args)
+{ prn(space, arg1); prn(space, args...); }
+
+ll mulmod(ll a,ll b,ll mod) 
+{ ll res=0; a=a%mod; 
+    while(b>0)
+    { if(b%2==1) res=(res+a)%mod; 
+      a=(a*2)%mod; b/=2; }
+    return res % mod; } 
+
+ll powmod(ll x,ll y,ll p) 
+{ ll res=1; x=x%p;
+	while(y>0) 
+	{ if (y&1) res=(res*x)%p; 
+	  y=y>>1; x=(x*x)%p; } 
+	return res; } 
+
+ll log(ll n, ll b)
+{ ll c=0;
+	while(n>(b-1))
+	{ c++; n/=b; } return c; }
+
+#define MOD 1000000007 //10^9+7
+#define pi 3.14159265358979323846
+#define f0(i,n) for(i=0;i<n;i++)
+#define f1(i,n) for(i=1;i<=n;i++)
+#define fd(i,n) for(i=n-1;i>=0;i--)
+#define fn(i,s,d) for(i=s;i<d;i++)
+#define pb push_back
+#define mp make_pair
+#define all(a) a.begin(),a.end()
+#define sz(a) a.size()
+#define pl pair<ll,ll>
+#define vpl vector<pl>
+#define vb vector<bool>
+#define vl vector<ll>
+#define vvl vector<vl>
+#define vs vector<string>
+#define ff first
+#define ss second
+#define um unordered_map
+#define dsort(v) sort(v); reverse(v);
+#define maxpq(v) priority_queue<v>
+#define minpq(v) priority_queue<v,vector<v>,greater<v>>
+
+//check overflow
+void solve()
+{
+	ll i,j;
+	ll n;
+	cin>>n;
+	string s;
+	f0(i,n)
+	{
+		char c;
+		cin>>c;
+		s.pb(c);
+	}
+	if(n%2==1)
+	{
+		f0(i,n)
+		{
+			if((s[i]-'0')%2==1)
+			{
+				prn(0,1);
+				return;
+			}
+			i++;
+		}
+		prn(0,2);
+		return;
+	}
+	else
+	{
+		f0(i,n)
+		{
+			i++;
+			if((s[i]-'0')%2==0)
+			{
+				prn(0,2);
+				return;
+			}
+		}
+		prn(0,1);
+		return;
+	}
+}
+
+int main()
+{
+
+	#ifdef Deeksha
+		freopen("input.txt", "r", stdin);
+	#endif
+	std::ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
+	// solve();/* 
+	ll t;
+	cin>>t;
+	for(ll tt=1;tt<=t;tt++)
+	{
+		// cout<<"Case #"<<tt<<": ";
+		solve();
+	}
+	//*/
+}
+
diff --git a/Codeforces/#671 (Div. 2)/B.cpp b/Codeforces/#671 (Div. 2)/B.cpp
new file mode 100644
index 0000000..85b4a91
--- /dev/null
+++ b/Codeforces/#671 (Div. 2)/B.cpp	
@@ -0,0 +1,116 @@
+/*
+	author: blair_
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+typedef long long ll;
+
+template <typename Arg1>
+void prn(bool space, Arg1&& arg1)
+{ cout<<arg1; if(space) cout<<" "; else cout<<"\n"; }
+template <typename Arg1, typename... Args>
+void prn(bool space, Arg1&& arg1, Args&&... args)
+{ prn(space, arg1); prn(space, args...); }
+
+ll mulmod(ll a,ll b,ll mod) 
+{ ll res=0; a=a%mod; 
+    while(b>0)
+    { if(b%2==1) res=(res+a)%mod; 
+      a=(a*2)%mod; b/=2; }
+    return res % mod; } 
+
+ll powmod(ll x,ll y,ll p) 
+{ ll res=1; x=x%p;
+	while(y>0) 
+	{ if (y&1) res=(res*x)%p; 
+	  y=y>>1; x=(x*x)%p; } 
+	return res; } 
+
+ll log(ll n, ll b)
+{ ll c=0;
+	while(n>(b-1))
+	{ c++; n/=b; } return c; }
+
+#define MOD 1000000007 //10^9+7
+#define pi 3.14159265358979323846
+#define f0(i,n) for(i=0;i<n;i++)
+#define f1(i,n) for(i=1;i<=n;i++)
+#define fd(i,n) for(i=n-1;i>=0;i--)
+#define fn(i,s,d) for(i=s;i<d;i++)
+#define pb push_back
+#define mp make_pair
+#define all(a) a.begin(),a.end()
+#define sz(a) a.size()
+#define pl pair<ll,ll>
+#define vpl vector<pl>
+#define vb vector<bool>
+#define vl vector<ll>
+#define vvl vector<vl>
+#define vs vector<string>
+#define ff first
+#define ss second
+#define um unordered_map
+#define dsort(v) sort(v); reverse(v);
+#define maxpq(v) priority_queue<v>
+#define minpq(v) priority_queue<v,vector<v>,greater<v>>
+
+//check overflow
+vl fib;
+
+void solve()
+{
+	ll i,j;
+	ll n;
+	cin>>n;
+	f0(i,fib.size())
+	{
+		if(fib[i]>n)
+			break;
+	}
+	prn(0,i);
+	return;
+}
+
+void pre()
+{
+	fib.pb(1);
+	ll help = 2;
+	ll last = 1;
+	while(true)
+	{
+		ll ans = 2*last;
+		if(ans>1e18)
+			break;
+		if(help>1e9)
+			break;
+		ans+=help*help;
+		if(ans>1e18)
+			break;
+		if(ans+fib.back()>1e18)
+			break;
+		fib.pb(fib.back()+ans);
+		last=ans;
+		help*=2;
+	}
+}
+
+int main()
+{
+
+	#ifdef Deeksha
+		freopen("input.txt", "r", stdin);
+	#endif
+	std::ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
+	pre();
+	// solve();/* 
+	ll t;
+	cin>>t;
+	for(ll tt=1;tt<=t;tt++)
+	{
+		// cout<<"Case #"<<tt<<": ";
+		solve();
+	}
+	//*/
+}
+
diff --git a/Codeforces/#671 (Div. 2)/C.cpp b/Codeforces/#671 (Div. 2)/C.cpp
new file mode 100644
index 0000000..977e872
--- /dev/null
+++ b/Codeforces/#671 (Div. 2)/C.cpp	
@@ -0,0 +1,122 @@
+/*
+	author: blair_
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+typedef long long ll;
+
+template <typename Arg1>
+void prn(bool space, Arg1&& arg1)
+{ cout<<arg1; if(space) cout<<" "; else cout<<"\n"; }
+template <typename Arg1, typename... Args>
+void prn(bool space, Arg1&& arg1, Args&&... args)
+{ prn(space, arg1); prn(space, args...); }
+
+ll mulmod(ll a,ll b,ll mod) 
+{ ll res=0; a=a%mod; 
+    while(b>0)
+    { if(b%2==1) res=(res+a)%mod; 
+      a=(a*2)%mod; b/=2; }
+    return res % mod; } 
+
+ll powmod(ll x,ll y,ll p) 
+{ ll res=1; x=x%p;
+	while(y>0) 
+	{ if (y&1) res=(res*x)%p; 
+	  y=y>>1; x=(x*x)%p; } 
+	return res; } 
+
+ll log(ll n, ll b)
+{ ll c=0;
+	while(n>(b-1))
+	{ c++; n/=b; } return c; }
+
+#define MOD 1000000007 //10^9+7
+#define pi 3.14159265358979323846
+#define f0(i,n) for(i=0;i<n;i++)
+#define f1(i,n) for(i=1;i<=n;i++)
+#define fd(i,n) for(i=n-1;i>=0;i--)
+#define fn(i,s,d) for(i=s;i<d;i++)
+#define pb push_back
+#define mp make_pair
+#define all(a) a.begin(),a.end()
+#define sz(a) a.size()
+#define pl pair<ll,ll>
+#define vpl vector<pl>
+#define vb vector<bool>
+#define vl vector<ll>
+#define vvl vector<vl>
+#define vs vector<string>
+#define ff first
+#define ss second
+#define um unordered_map
+#define dsort(v) sort(v); reverse(v);
+#define maxpq(v) priority_queue<v>
+#define minpq(v) priority_queue<v,vector<v>,greater<v>>
+
+//check overflow
+void solve()
+{
+	ll i,j;
+	ll n,k;
+	cin>>n>>k;
+	vl v(n);
+	ll same=0;
+	f0(i,n)
+	{
+		cin>>v[i];
+		if(v[i]==k)
+			same++;
+	}
+	if(same==n)
+	{
+		prn(0,0);
+		return;
+	}
+	if(same>0)
+	{
+		prn(0,1);
+		return;
+	}
+	ll sum=0;
+	f0(i,n)
+	{
+		sum+=v[i];
+	}
+	if(k==0)
+	{
+		if(sum==0)
+			prn(0,1);
+		else
+			prn(0,2);
+		return;
+	}
+	if(sum==k*n)
+	{
+		prn(0,1);
+	}
+	else
+	{
+		prn(0,2);
+	}
+}
+
+int main()
+{
+
+	#ifdef Deeksha
+		freopen("input.txt", "r", stdin);
+	#endif
+	std::ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
+	// solve();/* 
+	ll t;
+	cin>>t;
+	for(ll tt=1;tt<=t;tt++)
+	{
+		// cout<<"Case #"<<tt<<": ";
+		solve();
+	}
+	//*/
+}
+
diff --git a/Codeforces/#671 (Div. 2)/D1.cpp b/Codeforces/#671 (Div. 2)/D1.cpp
new file mode 100644
index 0000000..cd8d11f
--- /dev/null
+++ b/Codeforces/#671 (Div. 2)/D1.cpp	
@@ -0,0 +1,104 @@
+/*
+	author: blair_
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+typedef long long ll;
+
+template <typename Arg1>
+void prn(bool space, Arg1&& arg1)
+{ cout<<arg1; if(space) cout<<" "; else cout<<"\n"; }
+template <typename Arg1, typename... Args>
+void prn(bool space, Arg1&& arg1, Args&&... args)
+{ prn(space, arg1); prn(space, args...); }
+
+ll mulmod(ll a,ll b,ll mod) 
+{ ll res=0; a=a%mod; 
+    while(b>0)
+    { if(b%2==1) res=(res+a)%mod; 
+      a=(a*2)%mod; b/=2; }
+    return res % mod; } 
+
+ll powmod(ll x,ll y,ll p) 
+{ ll res=1; x=x%p;
+	while(y>0) 
+	{ if (y&1) res=(res*x)%p; 
+	  y=y>>1; x=(x*x)%p; } 
+	return res; } 
+
+ll log(ll n, ll b)
+{ ll c=0;
+	while(n>(b-1))
+	{ c++; n/=b; } return c; }
+
+#define MOD 1000000007 //10^9+7
+#define pi 3.14159265358979323846
+#define f0(i,n) for(i=0;i<n;i++)
+#define f1(i,n) for(i=1;i<=n;i++)
+#define fd(i,n) for(i=n-1;i>=0;i--)
+#define fn(i,s,d) for(i=s;i<d;i++)
+#define pb push_back
+#define mp make_pair
+#define all(a) a.begin(),a.end()
+#define sz(a) a.size()
+#define pl pair<ll,ll>
+#define vpl vector<pl>
+#define vb vector<bool>
+#define vl vector<ll>
+#define vvl vector<vl>
+#define vs vector<string>
+#define ff first
+#define ss second
+#define um unordered_map
+#define dsort(v) sort(v); reverse(v);
+#define maxpq(v) priority_queue<v>
+#define minpq(v) priority_queue<v,vector<v>,greater<v>>
+
+//check overflow
+void solve()
+{
+	ll i,j;
+	ll n;
+	cin>>n;
+	vl v(n);
+	f0(i,n)
+	cin>>v[i];
+	sort(all(v));
+	ll k=n-1;
+	k/=2;
+	prn(0,k);
+	vl ans(n);
+	ll count=0;
+	i=1;
+	j=0;
+	while(count<k)
+	{
+		ans[i]=v[j];
+		i+=2;
+		j++;
+		count++;
+	}
+	f0(i,n)
+	{
+		if(ans[i]==0)
+		{
+			ans[i]=v[j];
+			j++;
+		}
+	}
+	for(auto i:ans)
+		prn(1,i);
+	prn(0,"");
+}
+
+int main()
+{
+
+	#ifdef Deeksha
+		freopen("input.txt", "r", stdin);
+	#endif
+	std::ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
+	solve();
+}
+
diff --git a/Codeforces/#671 (Div. 2)/D2.cpp b/Codeforces/#671 (Div. 2)/D2.cpp
new file mode 100644
index 0000000..a2ef24d
--- /dev/null
+++ b/Codeforces/#671 (Div. 2)/D2.cpp	
@@ -0,0 +1,159 @@
+/*
+	author: blair_
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+typedef long long ll;
+
+template <typename Arg1>
+void prn(bool space, Arg1&& arg1)
+{ cout<<arg1; if(space) cout<<" "; else cout<<"\n"; }
+template <typename Arg1, typename... Args>
+void prn(bool space, Arg1&& arg1, Args&&... args)
+{ prn(space, arg1); prn(space, args...); }
+
+ll mulmod(ll a,ll b,ll mod) 
+{ ll res=0; a=a%mod; 
+    while(b>0)
+    { if(b%2==1) res=(res+a)%mod; 
+      a=(a*2)%mod; b/=2; }
+    return res % mod; } 
+
+ll powmod(ll x,ll y,ll p) 
+{ ll res=1; x=x%p;
+	while(y>0) 
+	{ if (y&1) res=(res*x)%p; 
+	  y=y>>1; x=(x*x)%p; } 
+	return res; } 
+
+ll log(ll n, ll b)
+{ ll c=0;
+	while(n>(b-1))
+	{ c++; n/=b; } return c; }
+
+#define MOD 1000000007 //10^9+7
+#define pi 3.14159265358979323846
+#define f0(i,n) for(i=0;i<n;i++)
+#define f1(i,n) for(i=1;i<=n;i++)
+#define fd(i,n) for(i=n-1;i>=0;i--)
+#define fn(i,s,d) for(i=s;i<d;i++)
+#define pb push_back
+#define mp make_pair
+#define all(a) a.begin(),a.end()
+#define sz(a) a.size()
+#define pl pair<ll,ll>
+#define vpl vector<pl>
+#define vb vector<bool>
+#define vl vector<ll>
+#define vvl vector<vl>
+#define vs vector<string>
+#define ff first
+#define ss second
+#define um unordered_map
+#define dsort(v) sort(v); reverse(v);
+#define maxpq(v) priority_queue<v>
+#define minpq(v) priority_queue<v,vector<v>,greater<v>>
+
+//check overflow
+void solve()
+{
+	ll i,j;
+	ll n;
+	cin>>n;
+	vl v(n);
+	f0(i,n)
+	cin>>v[i];
+	if(n<3)
+	{
+		prn(0,0);
+		for(auto i:v)
+			prn(1,i);
+		prn(0,"");
+		return;
+	}
+	sort(all(v));
+		
+	j=0;
+	vl ans(n);
+	for(i=1;i<n;i+=2)
+	{
+		ans[i]=v[j];
+		j++;
+	}
+	f0(i,n)
+	{
+		if(ans[i]==0)
+		{
+			ans[i]=v[j];
+			j++;
+		}
+	}
+	ll k=0;
+	f0(i,n)
+	{
+		if(i%2==1)
+		{
+			if(i!=n-1)
+			{
+				if(ans[i-1]>ans[i]&&ans[i]<ans[i+1])
+					k++;
+			}
+		}
+	}
+	ll k2=k;
+	vl ans2=ans;
+	for(auto &i:ans)
+		i=0;
+
+	j=0;
+	for(i=2;i<n;i+=2)
+	{
+		ans[i]=v[j];
+		j++;
+	}
+	f0(i,n)
+	{
+		if(ans[i]==0)
+		{
+			ans[i]=v[j];
+			j++;
+		}
+	}
+	k=0;
+	f0(i,n)
+	{
+		if(i%2==1)
+		{
+			if(i!=n-1)
+			{
+				if(ans[i-1]>ans[i]&&ans[i]<ans[i+1])
+					k++;
+			}
+		}
+	}
+	if(max(k,k2)==k)
+	{
+		prn(0,k);
+		for(auto i:ans)
+			prn(1,i);
+		prn(0,"");
+	}
+	else
+	{
+		prn(0,k2);
+		for(auto i:ans2)
+			prn(1,i);
+		prn(0,"");
+	}
+}
+
+int main()
+{
+
+	#ifdef Deeksha
+		freopen("input.txt", "r", stdin);
+	#endif
+	std::ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
+	solve();
+}