//satyaki3794
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define MOD (1000000007LL)
#define LEFT(n) (2*(n))
#define RIGHT(n) (2*(n)+1)
 
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
 
ll pwr(ll base, ll p, ll mod=MOD){
ll ans = 1;while(p){if(p&1)ans=(ans*base)%mod;base=(base*base)%mod;p/=2;}return ans;
}
 
 
ll gcd(ll a, ll b){
    if(b == 0)  return a;
    return gcd(b, a%b);
}



 
int main(){
 
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    ll n;
    cin>>n;

    ll lo = n*(n-1)/2+1, hi = n*(n+1)/2;
    lo = 2*lo-1;	hi = 2*hi-1;
    cout<<n*(lo+hi)/2;

    return 0;
}