home4_1

#include <iostream>

using namespace std;

int main()
{
    int n,x=0;
    cin >> n;
    if (n>0) {
        for (int i=0; i<n; i++) {
            x=x+i*i;
        }
        cout << x << endl ;
    }
    else {
        cout << "bang, bang!" << endl;
    }
    return 0;
}