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

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