from sys import stdin
n, m, *a = map(int, stdin.read().split())
maxbit = (1<<(m+1)) - 1

dp = [0 for i in range(n+1)]
dp[0] = 1
for i in range(n):
    dp[i+1] = (dp[i] | (dp[i] << a[i])) & maxbit

if dp[n] & (1<<m):
    ans = 0
else:
    print("{}".format(-1))
    exit()
ans = 0

dp2 = [0 for i in range(n+1)]
dp2[n] = 1<<m
for i in reversed(range(n)):
    if dp[i] & dp2[i+1]:
        ans += 0
    else:
        if (dp[i] << a[i]) & dp2[i+1] == dp2[i+1]:
            ans += 1
    dp2[i] = (dp[i] & dp2[i+1]) | (dp[i] & (dp2[i+1] >> a[i]))

print("{}".format(ans))