import sys,collections,math
sys.setrecursionlimit(10**7)
def Is(): return [int(x) for x in sys.stdin.readline().split()]
def Ss(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def S(): return input()

n = I()
x = I()
a = I()
b = I()
print(min( math.ceil(x/a), math.ceil((2**(n-1) - x)/b) ))