N, S, T, K = map(int, input().split())
A = list(map(int, input().split()))

INF = 1<<60

S, T = S-1, T-1

if A[S]+A[T] <= K:
    print(1)
else:
    MIN = INF
    for i in range(N):
        if i != S:
            MIN = min(MIN, A[i])
    if MIN+A[S] <= K and MIN+A[T] <= K:
        print(2)
    else:
        print(-1)