C :

#include<stdio.h>
int main()
{
int n;
while(scanf("%d",&n)!=EOF)
printf("%d\n",n*n-n+2);
return 0;
}

C++ :

#include<iostream>
using namespace std;
const int N(1001);
int f[N];
void init()
{
    f[1]=2;
    for (int i=2;i<N;i++)
        f[i]=f[i-1]+2*(i-1);
}
int main()
{
    init();
    int n;
    while (cin>>n) cout<<f[n]<<endl;
    return 0;
}