#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    int j = k;
    int g = k;
    long pos = 0;
    while(j > 1){
        pos+=j;
        j--;
    }
    
    
    long pos2 = ((pos+1) * 2) - 1;
    
    pos = 0;
    while(g--){
        pos+=pos2;
        pos2-=2;
    }
    
    return pos;
}

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