n,s,t,k = map(int, input().split())
alist = list(map(int, input().split()))

ai = alist[s-1]
aj = alist[t-1]

if (ai + aj) <= k:
	print(1)
	exit()

if ai >= k:
	print(-1)
	exit()
if aj >= k:
	print(-1)
	exit()
	
	
alist[s-1] = 1 << 60
alist[t-1] = 1 << 60

x = min(alist)
if ((ai + x) <= k) & ((aj + x) <= k):
	print(2)
else:
	print(-1)