Codeforces 1180A. Alex and a Rhombus Solution

Solve in C++:


#include<bits/stdc++.h>
using namespace std;

int main()
{
    int a,b,n,r;

    while(scanf("%d",&n)!=EOF)
    {
        a=n-1;
        r=(n*n)+(a*a);
        printf("%d\n",r);
    }
}