#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  long long n, x;
  cin >> n >> x;
  long long ans = 3 * x + (n - x) + 4 * x - n;
  cout << ans;
  return 0;
}
