#!/usr/bin/ python3.8
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
from bisect import bisect_left, bisect_right

N = int(readline())
D = tuple(map(int, readline().split()))
x, y = map(int, read().split())
x = abs(x)
y = abs(y)


def dist_range(d):
    if d > x + y:
        return d - x - y, d + x + y
    else:
        return x + y - d, d + x + y


D_od = [x for x in D if x & 1]
D_ev = [x for x in D if not (x & 1)]
D_od.sort()
D_ev.sort()


def solve():
    if x == y == 0:
        return 0
    if x + y in D:
        return 1
    for d in D:
        d1, d2 = dist_range(d)
        A = D_od if d1 & 1 else D_ev
        if bisect_right(A, d2) - bisect_left(A, d1):
            return 2
    return - 1


print(solve())