#include<bits/stdc++.h>
using namespace std;


int main()
{
    long long int n,i=0,j,k;
    double ans;
    while(cin>>n && n)
    {
        i++;
        ans=((3)+sqrt(9+(8*n)))/2;
        int rans=ceil(ans);
        cout<<"Case "<<i<<": "<<rans<<endl;
    }
    return 0;
}