N = int(input())
X = int(input())
A = int(input())
B = int(input())

MAX = 1<<(N-1)
remain = MAX - X
a = X // A
b = remain // B
a = a + (1 if X % A != 0 else 0)
b = b + (1 if remain % B != 0 else 0)
print(min(a,b))