number= [int(x) for x in input().split()]
vegetable_number = number[0]
C = number[2]
for x in range(vegetable_number):
    D = (1 + C) * vegetable_number
    B = C * vegetable_number
    if number[3]>=D and number[1]>=B:
        print(vegetable_number)
        break
    vegetable_number = vegetable_number - 1

    if vegetable_number == 0:
        print("0")