import bisect

def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    n = int(input[idx])
    idx += 1
    d = list(map(int, input[idx:idx + n]))
    idx += n
    x = int(input[idx])
    y = int(input[idx + 1])
    idx += 2

    if x == 0 and y == 0:
        print(0)
        return

    M = abs(x) + abs(y)
    d_sorted = sorted(d)

    # Check 1 move
    pos = bisect.bisect_left(d_sorted, M)
    if pos < len(d_sorted) and d_sorted[pos] == M:
        print(1)
        return

    # Check 2 moves
    for d1 in d_sorted:
        low = max(M - d1, d1 - M)
        low = max(low, 1)  # since d_i >= 1
        high = d1 + M

        left = bisect.bisect_left(d_sorted, low)
        if left < len(d_sorted) and d_sorted[left] <= high:
            print(2)
            return

    print(-1)

if __name__ == "__main__":
    main()