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

S -= 1
T -= 1

mn = min(A)

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