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)

from operator import itemgetter
n,m=map(int,input().split())
l=[]
id_list=[]
for i in range(m):
  obj = list(map(int, input().split()))
  obj.append(i+1)
  l.append(obj)
l=sorted(l, key=itemgetter(0,1))
idx=0
for j in range(m):
  id_obj=[]
  if j == 0:
    idx=1
  else:

    if l[j][0] == l[j-1][0]:
      idx+=1
    else:
      idx =1
  id_obj.append(l[j][2])
  id_obj.append(str(l[j][0]).zfill(6)+str(idx).zfill(6))
  id_list.append(id_obj)
id_list = sorted(id_list)
for k in range(m):
  print(id_list[k][1])