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: Wrong Answer)

import sys

def i2nn():
    return sp2nn(sys.stdin.readline())

def ii2ss(n):
    return [sys.stdin.readline() for _ in range(n)]

def sp2nn(sp, sep=' '):
    return [int(s) for s in sp.split(sep)]

def ss2nn(ss):
    return [int(s) for s in list(ss)]

def main(N, ss):
    nn = [[] for _ in range(N+1)]
    for s in ss:
        p, y = sp2nn(s)
        nn[p].append(y)
    for n2 in nn:
        n2.sort()
    for i, n2 in enumerate(nn):
        for j, n in enumerate(n2):
            print('%06d%06d' % (i, j+1))

N, M = i2nn()
main(N, ii2ss(M))