ll n;
ll k;
ll a[MAXN];

int check(ll x)
{
    ll cr = 0;
    forn(i, n)
    {
        ll cur = 0;
        if (x == 1)
            cur = a[i];
        else
        {
            ll q = a[i];
            ll st = 0;
            while (q >= x)
                q /= 2, ++st;
            --st;
            cur = (1ll << st);
        }
        cr += cur;
        if (cr >= k)
            return 1;
    }
    return 0;
}

int solve()
{
    ll sum = 0;
    scanf("%lld %lld", &n, &k);
    forn(i, n)
        scanf("%lld", &a[i]), sum += a[i];
    if (sum < k)
        puts("-1"), exit(0);
    ll l = 1, r = (ll)1e7 + 1;
    while (r - l > 1)
    {
        ll mid = l + r >> 1ll;
        if (check(mid))
            l = mid;
        else
            r = mid;
    }
    cout << l;
    return 0;
}