1294 - Positive Negative Sign

#include<bits/stdc++.h>
using namespace std;
 
int main()
{
    long  T,n,m,c=1;
    scanf("%ld",&T);
    while(T--)
    {
        scanf("%ld%ld",&n,&m);
        printf("Case %ld: %ld\n",c++,(n*m)/2);
    }
    return 0;
}