#include <bits/stdc++.h>

using namespace std;
# define N 10001

typedef unsigned long long int ll;

ll sumOfGroup(ll y) {
    // Return the sum of the elements of the k'th group.
    ll dp[N];
dp[0]=0;
dp[1]=1;
for(ll i=2;i<N;i++)
{
    for(ll j=i*i-(i-1);j<=i*i+(i-1);j++)
    {    
        if(j%2==1)
        dp[i]+=j;
    }
    
  
   
}
    return dp[y];
    
    
}

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