#11650_좌표정렬

arr = []

for _ in range(int(input())):
    arr.append(list(map(int, input().split())))
 
arr.sort(key=lambda x:(x[0], x[1])) # x좌표 오름차순 후 y좌표 오름차순
 
for e in arr :
    print(str(e[0]) + " " + str(e[1]))