백준 11651번(Java)

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

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st;
		
		int N = Integer.parseInt(br.readLine());
		
		int[][] arr = new int[N][2];
		
		for(int i=0; i<N; i++) {
			st = new StringTokenizer(br.readLine());
			arr[i][0] = Integer.parseInt(st.nextToken());
			arr[i][1] = Integer.parseInt(st.nextToken());
		}
		
		Arrays.sort(arr, (n1,n2)->{
			if(n1[1] == n2[1]) {
				return n1[0] - n2[0];
			} else {
				return n1[1] - n2[1];
			}
		});
		
		StringBuilder sb = new StringBuilder();
		for(int i=0; i<N; i++) {
			sb.append(arr[i][0]+" "+arr[i][1]).append('\n');
		}
		System.out.println(sb);
	}
}