N,S,T,K=map(int, input().split())
A=list(map(int, input().split()))
if A[S-1]+A[T-1]<=K:
  print(1)
  exit()
  
if A[S-1]+min(A)<=K and min(A)+A[T-1]<=K:
  print(2)
  exit()
print(-1)