9-4.최대 수입 수케쥴 문제 질문있습니다!!

9-4.최대 수입 수케쥴 문제 질문있습니다!!

import java.util.ArrayList;
import java.util.Collections;
import java.util.PriorityQueue;
import java.util.Scanner;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();

        ArrayList<Point> arrayList = new ArrayList<>();
        for (int i = 0; i < N; i++) {
            int x = sc.nextInt();
            int y = sc.nextInt();
            arrayList.add(new Point(x, y));
        }
        Collections.sort(arrayList);
        PriorityQueue<Integer> priorityQueue = new PriorityQueue<>(Collections.reverseOrder());
        int tmp = arrayList.get(0).y;
        int answer = 0;
        for (int i = 0; i < arrayList.size(); i++) {
            if (arrayList.get(i).y < tmp) {
                answer += priorityQueue.poll();
                tmp = arrayList.get(i).y;
            }
            priorityQueue.add(arrayList.get(i).x);
            if (i == arrayList.size() - 1) {
                answer += priorityQueue.poll();
            }
        }

        System.out.println(answer);
        int j=0;
        
    }


}

class Point implements Comparable<Point> {
    int x;
    int y;

    Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    @Override
    public int compareTo(Point o) {
        return o.y-this.y;
    }
}

답이 잘 나오는데 왜 오답인지 궁금합니다 ㅠㅠ