#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    // Return the sum of the elements of the k'th group.
    if(k==1){
        return 1;
    }
    long int sum = 0;
    for(int i=0;i<k;i++){
        sum+=i;
    }
    
    long int n1 = (2*(sum))+1;
    long int sum1=0;
    //cout<<sum<<" "<<n1<<" ";
    for(int i=0;i<k;i++){
        sum1+=n1;
        //cout<<sum1<<" "<<n1<<"\n";
        n1+=2;
    }
    return sum1;
}

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