#include <algorithm>
#include <iostream>
#include <iterator>
#include <numeric>
#include <sstream>
#include <fstream>
#include <cassert>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <string>
#include <cstdio>
#include <vector>
#include <cmath>
#include <queue>
#include <deque>
#include <stack>
#include <list>
#include <map>
#include <set>

using namespace std;

int main()
{
    int tc;
    cin>>tc;
    for(int i=1;i<=tc;i++){
        int n,k,x;
        cin>>n>>k>>x;
        int tw=n*(n+1)/2;
        int sn=k*(2*x+(k-1)*1)/2;
        printf("Case %d: %d\n",i,tw-sn);
    }
    return 0;
}