matu124.cpp

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;

int main()
{
	char c;
	float a, b, result(0);
	int tag(1);
	cin>>a>>b>>c;
	switch(c){
		case '+':
			result= a+b;
			break;
		case '-':
			result= a-b;
			break;
		case '*':
			result= a*b;
			break;
		case '/':
			if (fabs(b)< 1e-6){
				cout<<"divide 0"<<endl;
				tag= 0;
				break;
			}
			result= a/b;
			cout<<result<<endl;
			break;
		default:
			tag= 0;
			cout<<"invalid operation"<<endl;
			break;
	}
	if (tag){
		cout<<result<<endl;
	}

	return 0;
}