#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    unsigned long firstNumInGroup = 0, everyOther = 0;
    unsigned long long total = 0;
    
    for (int i = k - 1; i > 0; --i){
        firstNumInGroup += k;
    }
    ++firstNumInGroup; //total is now equal to first number in group
    
    for (int i = 0; i < k; ++i){
        total = total + (firstNumInGroup + everyOther);
        everyOther += 2;
    }
    
    return total;
}

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