TONG C++

#include <bits/stdc++.h>
using namespace std;
int n,s;
int main()
{
    freopen("tong.inp","r",stdin);
    freopen("tong.out","w",stdout);
    cin>>n;
    s = n*(n+1)/2;
    cout<<"Tong tu 1 den "<<n<<" la "<<s;
}