Problems
Triangular web
include<bits/stdc++.h> using namespace std; int main(){ long long t,n,r=1,i; cin>>n; for(i=0; i<=1000000000; i++){ t=6*i; r+=t; if(n==i){ cout<<r; break;} } }
include<stdio.h>
int main(){ long long n; scanf("%d",&n); printf("%ld",3n(n+1)+1); }
include <bits/stdc++.h>
using namespace std;
int main() {
long long n;
cin>>n;
cout<<(n*n)*3+(n*3)+1;
return 0;
}