Solution of 1294 - Positive Negative Sign ( Light Oj )

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

int main()
{
    long long m, n, test, t, ans;
    scanf("%lld", &test);
    for(t=1; t<=test; t++)
    {
        scanf("%lld%lld", &n, &m);
        ans = (n*m)/2;
        printf("Case %lld: %lld\n", t, ans);
    }
}