def I(): return map(int, input().split())

N, S, T, K = I()
S -= 1
T -= 1
*A, = I()

if A[S] + A[T] <= K:
	print(1)
elif A[S] + min(A) <= K and min(A) + A[T] <= K:
	print(2)
else:
	print(-1)