package main

import (
	"fmt"
)

func main() {
	var n, k int
	if _, err := fmt.Scan(&n, &k); err == nil {
		minMoves := 3 * n
		if k-1 < n-k {
			minMoves += k - 1
		} else {
			minMoves += n - k
		}
		fmt.Println(minMoves)
	}
}