s = str(input())
s = s.split(" ")

veg = int(s[0])
meat = int(s[1])
times = int(s[2])
max_ = int(s[3])

total = 0

while veg > 0 or meat > 0 or max_ > 0:
    if veg * (1 + times) <= max_ and times <= meat:
        total += 1
        meat -= times
        veg -= 1
        max_ -= (1 + times)
    else:
        veg = 0
        break

print(total)