Hey guys, please help me debug this code for d1 in today's contest, it got WA on test 24(you can imagine how I felt after seeing that during the contest). Here's the code:

ll mex2(vi a)
{
    int n = a.size();
    map<int,int>hash;
    loop(i , 0 , n - 1)
    {
        hash[a[i]]++;
    }
    ll cnt = 0 , i = 0;
    while(true)
    {
        if(hash[i] == 0)
        {
            if(cnt)
            {
                return i;
            }
            cnt++;
        }
        i++;
    }
}
void print(ll n)
{
    cout << n << endl;
}

void solve()
{
    ll n , m;
    cin >> n >> m;
    vector<vi>a(n);
    int s , temp;
    loop(i , 0 , n - 1)
    {
        cin >> s;
        loop(j , 0 , s - 1)
        {
            cin >> temp;
            a[i].push_back(temp);
        }
    }
    ll ans = 0;
    loop(i , 0 , n - 1)
    {
        ans = max(ans , mex2(a[i]));
    }
    int x = ans;
    ans *= min(ans + 1 , m + 1);
    if(x > m)
    {
        print(ans);
        return;
    }
    else
    {
        ans -=((x)*(x + 1))/2;
        ans += (m*(m + 1))/2;
        print(ans);
    }

}

Also, I am sorry if this is not supposed to be here and there is a separate place for debugging related doubts. `