#include <bits/stdc++.h>
using namespace std;
void solve();
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0);
  int t = 1;
  while (t--) solve();
  return 0;
}
long long n, k;
void solve() {
  cin >> n >> k;
  long long ans = min(n - k, k - 1) + n - 1 + n + 1 + n;
  cout << ans;
}
