n, s, t, k = map(int, input().split())
a = list(map(int, input().split()))

assert 1 <= n <= 2 * 10 ** 5
assert 1 <= s <= n
assert 1 <= t <= n
assert s != t
assert 1 <= k <= 10 ** 9

for x in a:
    assert 1 <= x <= 10 ** 9

s -= 1
t -= 1

if a[s] + a[t] <= k:
    print(1)
elif min(a) + max(a[s], a[t]) <= k:
    print(2)
else:
    print(-1)