Light OJ 1294

#include<bits/stdc++.h>
#include<cmath>
#define pi 2*acos(0.0)
using namespace std;

int main()
{
    long long int t,i;
    cin>>t;
    for(i=1;i<=t;i++){
        long long int x,y;
        cin>>x>>y;
        cout<<"Case "<<i<<": "<<(x*y)/2<<endl;
    }
    return 0;
}