a, b, n, m = map(int, input().split())
l = 0
r = 10**18
while r - l > 1:
    mid = (l + r) // 2
    e = a
    f = b
    if e < mid:
        f -= (mid - e) * m
        e = mid
    if f < mid:
        e -= (mid - f) * n
        f = mid
    if e >= mid and f >= mid:
        l = mid
    else:
        r = mid
print(l)