注意按照右端点排序的语句：list接收返回_Collectors.toList()__getR____collect

list=list.stream().sorted(Comparator.comparing(Pair::getR)).collect(java.util.stream.Collectors.toList());

class Pair和class Main并列，即不可同时两个public class

import java.util.*;
class Main{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        List<Pair> list=new ArrayList<>();

        for(int i=0;i<n;i++){
            list.add(new Pair(sc.nextInt(),sc.nextInt()));
        }
        list=list.stream().sorted(Comparator.comparing(Pair::getR)).collect(java.util.stream.Collectors.toList());

        int tar=list.get(0).getR(),res=1;
        for(int i=1;i<list.size();i++){
            int t=list.get(i).getL();
            if(t>tar) {tar=list.get(i).getR();res++;}
        }
        System.out.println(res);
    }
}
class Pair
{
    int l;
    int r;
    Pair(int l,int r){this.l=l;this.r=r;}
    public int getL(){return l;}
    public int getR(){return r;}
}