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

int main()
{
    long tst,n,m,c;
    cin>>tst;

    for(c=1;c<=tst;c++)
    {
        cin>>n>>m;
        printf("Case %ld: %ld\n",c,n*m/2);
    }
    return 0;
}