def main():
    n, s, t, k = map(int, input().split())
    *a, = map(int, input().split())
    if a[s-1] + a[t-1] <= k:
        print(1)
    elif min(a) + a[s-1] <= k and min(a) + a[t-1] <= k:
        print(2)
    else:
        print(-1)


if __name__ == "__main__":
    main()