import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# inf = (1 << 31)-1
md = 10**9+7
# md = 998244353

n, k = LI()
aa = LI()

mask = (1 << k+1)-1
ll = [1]
for a in aa:
    ll.append((ll[-1] << a & mask) | ll[-1])

if (ll[-1] >> k) == 0:
    print(-1)
    exit()

rr = [1 << k]
for a in aa[::-1]:
    rr.append(rr[-1] >> a | rr[-1])
rr.reverse()

# print(*[bin(a)[2:].zfill(k+1) for a in ll])
# print(*[bin(a)[2:].zfill(k+1) for a in rr])

ans = n
for i in range(n):
    if ll[i] & rr[i+1]:
        # pDB(i)
        ans -= 1

print(ans)