#include <bits/stdc++.h>

using namespace std;

long long gaussSum(long long k)
{
    return (k*(k+1))/2;
    
}

long long oddSum(long long k)
{
    return k*k;
}

long sumOfGroup(int k) 
{
    long long unsigned sum=0;
    sum=oddSum(gaussSum(k-1)+k)-oddSum(gaussSum(k-1));
    return sum;
}

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