Two string - C++ - set class, insert, find, end functions

Twostring6.cpp

#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>

using namespace std;

int main()
{
string A,B;
int T;
cin>>T;
while(T--)
{
    cin>>A>>B;
    set<char>S;
    int n=A.length();
    int m=B.length();
    for(int i=0;i<n;i++)
        S.insert(A[i]);
    bool flag=false;
    for(int j=0;j<m;j++)
        if(S.find(B[j])!=S.end())
    {
        flag=true;
        break;
    }
    if(flag)
        cout<<"YES"<<endl;
    else
        cout<<"NO"<<endl;
}
return 0;
}