#include <bits/stdc++.h>

using namespace std;

long long sumOfGroup(long k) {
    long long sum1=0,sum2=0;
    long long t=k*(k-1)/2;
    long long t1=(k+1)*k/2;
    sum1=(t*t);
    sum2=(t1*t1);
    sum2-=sum1;
    return sum2;
}

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