#include<bits/stdc++.h>
#include<memory.h>
using namespace std;
#define IN freopen("input.txt","r",stdin)
#define OUT freopen("output.txt","w",stdout)
#define pf printf
#define sf scanf
#define pb push_back
#define MAX 1000005
#define FOR(i,n) for(i=0;i<n;i++)
#define all(x) x.begin(),x.end()
#define mod7 1000000007
typedef long long int ll;
typedef long double lld;
const double PI=2*acos(0.0);
struct vpair{
    int a;
    int b;
    vpair(int a,int b){this->a=a;this->b=b;}
};
bool cmp(vpair &a,vpair &b){
    if(a.a<b.a)return true;
    else if(a.a==b.a){
        if(a.b>b.b)return true;
        else return false;
    }else{
        return false;
    }
}
int CASE=1,TEST=0;
ll n,m,u,w;
ll a,b,c,d;
ll ans;
int main(void){
    sf("%lld",&n);
    m=(n*(n+1))/2;
    w=((n-1)*n)/2;
    a=(2*w)+1;
    a=a*2;
    a+=(n-1)*2;
    a=a*n;
    a=a>>1;
    pf("%lld\n",a);
}