in java i used a TreeSet

public static void main(String[] args) { Scanner s = new Scanner(System.in);

    int q = s.nextInt();
    Set<Integer> heap = new TreeSet<>();
    for (int i = 0; i<q;i++) {
        int qt = s.nextInt();
        switch (qt) {
            case 1:
                heap.add(s.nextInt());
                break;
            case 2:
                heap.remove(s.nextInt());
                break;
            case 3:
                System.out.println( heap.stream().findFirst().get() );
                break;
        }
    }
                    s.close();
}




    }

    s.close();
}