N, M = gets.split.map(&:to_i)

def f(x)
  sum = 1
  m = x
  remain = N

  while remain > 1 && m > 1
    sum += m

    m = (m + 1) / 2

    remain -= 1
  end

  if m != 1
    -1
  else
    sum + remain - 1
  end
end

ok = 1
ng = M + 1

while (ok - ng).abs >= 2
  x = (ok + ng) / 2
  val = f(x)

  if val != -1
    ok = x
  else
    ng = x
  end
end

puts f(ok)