a, b, c, d = map(int, input().split())

if 0 < a <= b <= d <= 100 and c > 0:
    if a >= b // c  and a + b // c <= d:
        print(b // c)
    elif a < b // c and a + a * c <= d:
        print(a)
    elif a < b // c and a + a * c > d:
        print(d // (c + 1))
    else:
        print(0)