#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(long k) {
    
    long sum,res=0;
    sum= k*(k-1) + 1;
    for(long i=sum,j=0; j<k; i=i+2,j++){
        res += i;
    }
    return (res);
}

int main() {
    long k;
    cin >> k;
    long answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}