a = gets.chomp.split(" ").map(&:to_i)
stub = 0
if a[0] / 2.0 > a[1]
stub = a[1]
else
stub = a[0] - a[1]# - 1
end

if a[0] % 2 == 0
stub = 1 if stub > a[0] / 4 && stub < a[0] / 2
p a[0]* 3 - stub * 3
else
p a[0]* 3 - 3
end

