import sys
from itertools import combinations
readline = sys.stdin.readline
n = int(readline())
d = sorted(map(int, readline().split()))
x, y = map(int, readline().split())
max_xy = abs(x) + abs(y)
def solve():
    if max_xy in d:
        return 1
    if len(d) == 1:
        return -1
    if max_xy > d[-1] + d[-2]:
        return -1
    for a, b in combinations(d, 2):
        if max_xy == a + b or max_xy == abs(a - b):
            return 2
    return -1
print(solve())