def chevyshev(x):
    ans = []
    for i in range(2*x+1):
        for j in range(2*x+1):
            if max(abs(i-x), abs(j-x)) == x:
                ans.append([i-x, j-x])
    return ans


def bfs(list, x, y):
    queue = [[0, 0]]
    visited = []
    cnt = 0
    while queue:
        stack = queue[:]
        queue.clear()
        while stack:
            label = stack.pop(0)
            if (label[0] == x) and (label[1] == y):
                return cnt
            if label in visited:
                continue
            visited.append(label)
            for i in list:
                queue = [[label[0] + i[0], label[1] + i[1]]] + queue
        cnt += 1
    return -1

if __name__ == '__main__':
    n = int(input())
    d = list(map(int, input().split()))
    x, y = [int(i) for i in input().split()]
    tmp = []
    for i in d:
        tmp = tmp + chevyshev(i)
    print(bfs(tmp, x, y))