condition = list(input().split())

vegitable = int(condition[0])
origin_meet = int(condition[1])
rate = int(condition[2])
origin_all = int(condition[3])

for i in range(vegitable):
    meet = i * rate
    if (meet > origin_meet):
        i = i-1
        exit
    all = i + meet
    if (all > origin_all):
        i=i-1
        exit
print(i)