#include <bits/stdc++.h>
using ll = long long;
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  int N, K;
  cin >> N >> K;
  ll total = N + 1;
  total += N;
  total += min(2 * (K - 1) + (N - K), 2 * (N - K) + K - 1);
  cout << total << "\n";
  return 0;
}
