from bisect import bisect

def main():
    N = int(input())
    D = tuple(map(int, input().split()))
    X, Y = map(int, input().split())

    p = abs(X) + abs(Y)
    if p == 0:
        print(0)
    elif N == 1:
        if p % D[0]:
            print(-1)
        else:
            print(p // D[0])
        return

    div_ = []
    mod_ = []
    apndd = div_.append
    apndm = mod_.append
    for i in D:
        d, m = divmod(max(p, i), min(p, i))
        apndd(d)
        apndm(m)

    num = []
    apnd = num.append
    for i, j in zip(div_, mod_):
        if j == 0 or j in D:
            apnd(i)

    print(min(num) + 1)

main()