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