#!/usr/bin/python2
# -*- coding: utf-8 -*-
# †
from bisect import bisect_left
def index(arr, x):
    i = bisect_left(arr, x)
    return i if i!=len(arr) and arr[i]==x else -1
exists = lambda arr, x: index(arr, x) >= 0

n = int(raw_input())
d = map(int, raw_input().split())
d.sort()

def f(x, y):
    if (x, y) == (0, 0):
        return 0
    dist = abs(x) + abs(y)
    # 1回でいけるか
    if exists(d, dist):
        return 1
    # 2回でいけるか
    for i in xrange(n):
        left = dist - d[i]
        if left < 0:
            break
        if exists(d[:i], left) or exists(d[i+1:], left):
            return 2
    return -1

x, y = map(int, raw_input().split())
res = f(x, y)
print res