#include <bits/stdc++.h>
using namespace std;
template <class BidirIt>
BidirIt prev(BidirIt it,
             typename iterator_traits<BidirIt>::difference_type n = 1) {
  advance(it, -n);
  return it;
}
template <class ForwardIt>
ForwardIt next(ForwardIt it,
               typename iterator_traits<ForwardIt>::difference_type n = 1) {
  advance(it, n);
  return it;
}
const double EPS = 1e-9;
const double PI = 3.141592653589793238462;
template <typename T>
inline T sq(T a) {
  return a * a;
}
int main() {
  long long n, x;
  cin >> n >> x;
  cout << 3 * x + (n - x) + 3 * (n - 2 * x) << endl;
  return 0;
}
