import bisect

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

D = abs(x) + abs(y)

if D == 0:
    print(0)
else:
    sorted_d = sorted(d)
    idx = bisect.bisect_left(sorted_d, D)
    if idx < len(sorted_d) and sorted_d[idx] == D:
        print(1)
    else:
        found = False
        for di in sorted_d:
            low = max(0, D - di)
            high = di + D
            left = bisect.bisect_left(sorted_d, low)
            right = bisect.bisect_right(sorted_d, high)
            if left < right:
                found = True
                break
        print(2 if found else -1)