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

if a[s-1] + a[t-1] <= k:
    print(1)
elif minv + a[s-1] <= k and minv + a[t-1] <= k:
    print(2)
else:
    print(-1)