N=int(input())
D=list(map(int,input().split()))
x,y=map(int,input().split())

Distance=abs(x)+abs(y)

if Distance in D:
    print(1)
    exit()

S=set(D)
for d in D:
    x=Distance-d

    if x>=0:
        if x in S:
            print(2)
            exit()
    else:
        if -x in S:
            print(2)
            exit()

print(-1)