from collections import defaultdict

def f(A):
    A=["*"]+A
    DP=[-1]*(K+1); DP[0]=0

    for i,a in enumerate(A[1:],1):
        for y in range(K,a-1,-1):
            if DP[y-a]>=0 and DP[y]==-1:
                DP[y]=i
    if DP[K]==-1:
        return None

    X=[]; x=K
    while x>0:
        X.append(DP[x])
        x-=A[DP[x]]
    return X
#==================================================
N,K=map(int,input().split())
A=list(map(int,input().split()))
A.sort()

assert (N<=10**4) and (K<=10**3)

P=f(A)
if P==None:
    exit(print(-1))

Q=[N-k+1 for k in f(A[::-1])]

C=defaultdict(int)
for a in A:
    C[a]+=1

D=defaultdict(int)
for a in set(P)&set(Q):
    D[a]+=1

Ans=0
for a in C:
    if C[a]==D[a]:
        Ans+=C[a]

print(Ans)