Problem:
Score: 300 points

Problem Statement

In Republic of Atcoder, there are N prefectures, and a total of M cities that belong to those prefectures.

City i is established in year Y_i and belongs to Prefecture P_i.

You can assume that there are no multiple cities that are established in the same year.

It is decided to allocate a 12-digit ID number to each city.

If City i is the x-th established city among the cities that belong to Prefecture i, the first six digits of the ID number of City i is P_i, and the last six digits of the ID number is x.

Here, if P_i or x (or both) has less than six digits, zeros are added to the left until it has six digits.

Find the ID numbers for all the cities.

Note that there can be a prefecture with no cities.

Constraints

1 \leq N \leq 10^5

1 \leq M \leq 10^5

1 \leq P_i \leq N

1 \leq Y_i \leq 10^9

Y_i are all different.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N M
P_1 Y_1
:
P_M Y_M

Output

Print the ID numbers for all the cities, in ascending order of indices (City 1, City 2, ...).

Sample Input 1

2 3
1 32
2 63
1 12

Sample Output 1

000001000002
000002000001
000001000001

As City 1 is the second established city among the cities that belong to Prefecture 1, its ID number is 000001000002.

As City 2 is the first established city among the cities that belong to Prefecture 2, its ID number is 000002000001.

As City 3 is the first established city among the cities that belong to Prefecture 1, its ID number is 000001000001.

Sample Input 2

2 3
2 55
2 77
2 99

Sample Output 2

000002000001
000002000002
000002000003

Solution in Python (3.4.3) (judge verdict: Accepted)

#ABC113 C
#N個の県に合計M個の市がある
#市iが誕生したのはYi年で県Piに属する
#市iが県Piのなかでx番目に誕生しているとき,上6桁がPiで下6桁がxとなる番号を振りたい
#すべての市に認識番号を振り,iの順に出力せよ
#ただし市が1つも属さない県も存在しうる

#愚直な方針
#[i,Pi,Yi]を要素とする多重リストをつくる
N, M = map(int, input().split(' '))
city = []
for i in range(M):
	#[i,Pi,Yi]からなる多重リストをつくる
	city.append([i+1]+list(map(int, input().split(' '))))

#Pi->Yiの順番に多段階ソート (Piの数のオーダーは10**5)
from operator import itemgetter
city = sorted(city, key=itemgetter(1,2))

#各要素(=リスト)の末尾にxを追加する
#ただしxは要素をたどるごとに1ずつ増やしていくがPiが変わったら1にリセットする
x = 1
for n in range(M):
	if n==0:
		city[n].append(1)
	else:
		if city[n][1] != city[n-1][1]:
			x = 1
		else:
			x += 1
		city[n].append(x)			

#リストをふたたびiでソート
city = sorted(city, key=lambda l: l[0])

#認識番号をゼロパディングしてPi6桁+x6桁で出力
for c in city:
	print(str(c[1]).zfill(6) + str(c[3]).zfill(6))