https://velog.io/@letsbebrave/백준-11650번-좌표-정렬하기
from sys import stdin
n = int(stdin.readline())
arr = [0] * n
for i in range(n):
arr[i] = list(map(int, stdin.readline().split()))
arr = sorted(arr, key= lambda x:(x[1], x[0]))
for i in range(n):
print(arr[i][0], arr[i][1])