N,S,T,K=map(int,input().split())
A=list(map(int,input().split()))

S-=1
T-=1

if A[S-1]+A[T-1]<=K:
    print(1)
    exit()

MIN=min(A)

if A[S-1]+MIN<=K and A[T-1]+MIN<=K:
    print(2)
else:
    print(-1)