can't figure out how this code exceeds memory limit.
    queue<int> Q;
    multiset<int, greater<int> > S;
    for (int i = 0; i < M; ++i)
    {
        int temp;
        cin >> temp;
        Q.push(temp);
        S.insert(temp);
    }
    while (true)
    {
        cout << *(S.begin()) << endl;

        int toRemove = Q.front();
        Q.pop();
        S.erase(S.find(toRemove));

        int temp;
        cin >> temp;
        if (temp == -1) break;
        Q.push(temp);
        S.insert(temp);
    }