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

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

a = A[T-1]
res=[]
for i in range(1, N+1):
    res.append([A[i-1], i])

res = sorted(res, key=lambda x: x[0])

if min(A) == a:
    if a + res[1][0] <= K:
        print(2)
    else:
        print(-1)
else:
    if res[0][0] + a <= K:
        print(2)
    else:
        print(-1)