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