#include <bits/stdc++.h>

using namespace std;

unsigned long long sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    if(k==1)
        return 1;
    unsigned long long newK=k;
    unsigned long long prevs = (newK-1)*newK/2;
    unsigned long long first=2*prevs+1;
    
    unsigned long long last = first+2*(newK-1);
    unsigned long long ret = (first+last)/2*newK;
    return ret;
}

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