import sys
import bisect

n = int(sys.stdin.readline())
d_list = list(map(int, sys.stdin.readline().split()))
x, y = map(int, sys.stdin.readline().split())

D = abs(x) + abs(y)

if D == 0:
    print(0)
    sys.exit()

d_set = set(d_list)
if D in d_set:
    print(1)
    sys.exit()

# Preprocess even and odd lists, sorted
even = []
odd = []
for d in d_list:
    if d % 2 == 0:
        even.append(d)
    else:
        odd.append(d)

even.sort()
odd.sort()

found = False

for d1 in d_list:
    K = max(D - d1, 0)
    target_parity = (D + d1) % 2
    target = even if target_parity == 0 else odd
    if not target:
        continue
    idx = bisect.bisect_left(target, K)
    if idx < len(target):
        found = True
        break

print(2 if found else -1)