JAVA AC代码:

import java.util.*;
import java.util.StringTokenizer;
import java.io.*;

public class Main {

	public static void main(String[] args) {
		int n=in.nextInt();
		PriorityQueue<Integer> q=new PriorityQueue<>((o1,o2)->Integer.compare(o2, o1));//实现大的在前面
		Map<Integer,Integer> map=new HashMap<>();//记录每个数有多少个
		while(n-->0){
			int op=in.nextInt();
			if(op==1) {
				int x=in.nextInt();
				q.add(x);
				map.put(x,map.getOrDefault(x, 0)+1);
			}else if(op==2) {
				int x=in.nextInt();
				out.println(map.getOrDefault(x, 0));
			}else if(op==3) {
				int x=in.nextInt();
				if(q.contains(x)) {
					q.remove(x);
					map.put(x,map.get(x)-1);
				}
			}else if(op==4) {
				int x=in.nextInt();
				while(q.contains(x)) {
					q.remove(x);
				}
				map.remove(x);
			}else if(op==5) {
				out.println(q.size());
			}else if(op==6) {
				out.println(q.peek());
			}else {
				if(!q.isEmpty()) {
					int x=q.poll();
					map.put(x, map.get(x)-1);
			}}
		}
		out.close();
	}
	
	

	static FastReader in=new FastReader();
	static PrintWriter out=new PrintWriter(System.out);
	static class FastReader{
		static BufferedReader br;
		static StringTokenizer st;
		FastReader(){
			br=new BufferedReader(new InputStreamReader(System.in));
		}
		String next() {
			String str="";
			while(st==null||!st.hasMoreElements()) {
				try {
					str=br.readLine();
				}catch(IOException e) {
					throw new RuntimeException(e);
				}
				st=new StringTokenizer(str);
			}
			return st.nextToken();
		}
		int nextInt() {
			return Integer.parseInt(next());
		}
		double nextDouble() {
			return Double.parseDouble(next());
		}
		long nextLong() {
			return Long.parseLong(next());
		}
	}
	
}