1366B Shuffle.cpp

#include <bits/stdc++.h>
 
using namespace std;

template<class C> void mini(C&a, C b){ a=min(a, b);}
template<class C> void maxi(C&a, C b){a=max(a,b);}
#define sz(x) x.size()
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define forall(it,s) for(auto it = s.begin(); it != s.end(); ++it)
#define F0(i,n) for(int i = 0; i < n; i++)
#define F1(i,n) for(int (i) = 1; i <= n; i++)
#define F0R(i,n) for(int (i) = n-1; i >= 0; i--)
#define F1R(i,n) for(int (i) = n; i >= 1; i--)
#define REP(i,a,b) for(int i = a; i <= b; i++)
#define REPR(i,a,b) for(int i = a; i >= b; i--)
#define INF 1e9
#define todo(v) v.begin(),v.end()
#define eps 0.000000000001
#define mod 1000000007
#define PI acos(-1.0)
#define ll long long

void solve(){
	ll n,x,m,l,r;
	cin >> n >> x >> m;
	l = x;
	r = x;
	F0(i,m){
		ll li, ri;
		cin >> li >> ri;
		if((li <= l && r <= ri) || (l <= ri && ri <= r) || (l <= li && li <= r)){
			l = min(l, li);
			r = max(r, ri);
		}
	}
	cout << (r-l) + 1 << endl;
}
int main(){
	int t;
	cin >> t;
	while(t--) solve();
	return 0;
}