#include <bits/stdc++.h> #define rep(i,n) for(int i = 0; i < (int)(n); i++) #define rrep(ri,n) for(int ri = (int)(n-1); ri >= 0; ri--) #define rep2(i,x,n) for(int i = (int)(x); i < (int)(n); i++) #define rrep2(ri,x,n) for(int ri = (int)(n-1); ri >= (int)(x); ri--) #define repit(itr,x) for(auto itr = x.begin(); itr != x.end(); itr++) #define rrepit(ritr,x) for(auto ritr = x.rbegin(); ritr != x.rend(); ritr++) #define ALL(x) x.begin(), x.end() using ll = long long; using namespace std; int main() { int k; cin >> k; if(k == 1) { cout << 6 << endl; return 0; } ll ans = (ll)k*2 + 1; ans *= ans; ans -= (ll)k*3 + (k-1); cout << ans << endl; return 0; }