#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(long k) {
    // Return the sum of the elements of the k'th group.
    long long n,p=0;
    //n=(k*(k+1))/2+1;
    //cout<<n;
    for(int i=0;i<k;i++)
    {  
        p+=((k*(k-1))+1)+2*i;
        
    }
    return p;
    
}

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