import bisect

n = int(input())
d = list(map(int, input().split()))
x, y = map(int, input().split())
D = abs(x) + abs(y)

d_set = set(d)
if D in d_set:
    print(1)
else:
    d_sorted = sorted(d)
    found = False
    for d1 in d_sorted:
        lower = max(D - d1, d1 - D)
        upper = d1 + D
        left = bisect.bisect_left(d_sorted, lower)
        right = bisect.bisect_right(d_sorted, upper)
        count = right - left
        if count >= 2:
            found = True
            break
    print(2 if found else -1)