#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    int sum = 0;
    int a = 1;
    int b = 1;
    int c = 0;
    while(a != k+1){
        b += c;
        c+=2;
        a++;
    }
    int i;
    for(int i=0;i<k;i++){
        sum+=b;
        b+=2;
    }
    return sum;
}

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