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