#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
   long x=k;
    x=x*(x-1);
   long i=x+1;
    long ans=0;
    while(k--){
        if(i%2!=0){
            ans+=i;
            i+=2;
        }
        else {
            i++;
            ans+=i;
            i+=2;
        }
    }
    return ans;
}




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