#include <bits/stdc++.h>

using namespace std;
long long int find(long long int k)
{
        long long int start=0;
        for(long long int i=k-1;i>0;i--)
        {
            start=start+i;
            
        }
        start=start*2+1;
   
        return start;
    
}
long long int sumOfGroup(long long int k) {
    long long int start=0;
    start=find(k);
    long long int i=start+2;
    k--;
    while(k>0)
    {
        
        start=start+i;
        i=i+2;
        k--;
    }
    return start;
}

int main() {
    long long int k;
    cin >> k;
    long long int answer=1;
    if(k!=1)
       answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}