N,S,T,K=map(int, input().split())
A=list(map(int, input().split()))
A=A[S-1:T]
if A[0]+A[-1]<=K:
  print(1)
  exit()
  
if A[0]+min(A)<=K and min(A)+A[-1]<=K:
  print(2)
  exit()
print(-1)