import sys
#input = sys.stdin.readline
input = sys.stdin.buffer.readline #文字列はダメ
#sys.setrecursionlimit(1000000)
#import bisect
#import itertools
#import random
#from heapq import heapify, heappop, heappush
#from collections import defaultdict 
#from collections import deque
#import copy
#import math
#from functools import lru_cache
#@lru_cache(maxsize=None)
#MOD = pow(10,9) + 7
#MOD = 998244353
#dx = [1,0,-1,0]
#dy = [0,1,0,-1]

def solve(A,K):
    N = len(A)
    dp = [[0]*(K+1) for _ in range(N+1)]
    dp[0][0] = 1 
    #配るDP
    for i in range(N):
        a = A[i]
        for j in range(K+1):
            #使わない場合
            dp[i+1][j] = max(dp[i+1][j], dp[i][j])
            #使う場合
            if j+a <= K:
                dp[i+1][j+a] = max(dp[i+1][j+a], dp[i][j])
    used = []
    if dp[N][K] == 0:
        return used
    v = K
    for i in reversed(range(N)):
        a = A[i]
        if v-a >= 0 and dp[i][v-a] == 1:
            used.append(i)
            v -= a

    return used

def main():
    N,K = map(int,input().split())
    A = list(map(int,input().split()))
    mx = [-1]*(1+K)
    mn = [-1]*(1+K)
    A.sort()
    for i,a in enumerate(A):
        if mn[a] == -1:
            mn[a] = i
        mx[a] = i

    X = solve(A,K)
    X.sort()
    #print(X)
    A.reverse()
    Y = solve(A,K)
    Y = sorted([N-1-y for y in Y])
    #print(X,Y)
    #print(mx)
    #print(mn)
    #print(Y)
    X = set(X)
    Y = set(Y)
    Z = X&Y
    if len(Z) == 0:
        print(-1);exit()
        
    ans = 0
    for v in range(1+K):
        if mx[v] == -1: continue
        num = mx[v] - mn[v] + 1 #値vはnum個ある
        if mx[v] in Z and mn[v] in Z:
            ans += num

    print(ans)
    

if __name__ == '__main__':
    main()