#define rep(i,n) for(int i=0;i<(int)(n);i++) #define ALL(v) v.begin(),v.end() typedef long long ll; #include <bits/stdc++.h> using namespace std; int main(){ ll k; cin>>k; if(k%2==0) cout<<4*k*k+2<<endl; else cout<<4*k*k+2*k-k/2*4<<endl; return 0; }