N,S,T,K=map(int,input().split())
a=list(map(int,input().split()))
mn,mni=10**9+1,-1
for i in range(N):
    if mn > a[i]:
        mn = a[i]
        mni = i

# Ai + At <= K ?
if a[S-1] + a[T-1] <= K:
    print(1)
elif a[S-1] + a[mni] <= K and a[mni] + a[T-1] <= K:
    print(2)
else:
    print(-1)