def main():
    n, s, t, k = map(int, input().split())
    A = list(map(int, input().split()))
    s, t = s-1, t-1
    if A[s] + A[t] <= k:
        return 1
    ma = min(A)
    if ma + A[s] <= k and ma + A[t] <= k:
        return 2
    return -1
        

print(main())