n,s,t,K=map(int,input().split())
a=list(map(int,input().split()))
s=a[s-1]
t=a[t-1]
a.sort()
if s+t<=K:
  print(1)
  exit()
if s+a[0]<=K and t+a[0]<=K:
  print(2)
  exit()
print(-1)