import sys
readline = sys.stdin.readline
n = int(readline())
pq = [[], []]
for i in map(int, readline().split()):
    pq[i % 2].append(i)
x, y = map(int, readline().split())
z = abs(x) + abs(y)
def solve():
    if z == 0: return 0
    if z in pq[0] or z in pq[1]: return 1
    pq[0].sort()
    pq[1].sort()
    if z % 2 == 0:
        if pq[0]:
            if pq[0][-1] * 2 >= z:
                return 2
        if pq[1]:
            if pq[1][-1] * 2 >= z:
                return 2
    else:
        while pq[0] and pq[1]:
            t1 = pq[0][-1]
            t2 = pq[1][-1]
            if t1 + t2 >= z and max(t1, t2) - min(t1, t2) <= z:
                return 2
            if t1 > t2:
                pq[0].pop()
            else:
                pq[1].pop()
    return -1
print(solve())