a, b, c, d = map(int, input().split(' '))
total = 0
cnt = 0

while(True):

    if a == 0 or b == 0:
        break

    total += c + 1
    a -= 1
    b -= c

    if total > d:
        break

    if not (b < 0):
        cnt += 1

print(cnt)