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)

#!/usr/bin/env python3
import sys


def solve(N: int, M: int, P: "List[int]", Y: "List[int]"):
    hashTable = {}

    for i in range(M):
        if hashTable.get(P[i]) == None:
            hashTable[P[i]] = [Y[i]]
        else:
            hashTable[P[i]].append(Y[i])
    
    # Year: idnumber
    answerTable = {}

    for key,value in hashTable.items():
        value.sort()
        
        for i,v in enumerate(value):
            answerTable[v] = str(key).zfill(6) + str(i+1).zfill(6)
    
    for i in range(M):
        print(answerTable[Y[i]])

    return


def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    P = [int()] * (M)  # type: "List[int]"
    Y = [int()] * (M)  # type: "List[int]"
    for i in range(M):
        P[i] = int(next(tokens))
        Y[i] = int(next(tokens))
    solve(N, M, P, Y)

if __name__ == '__main__':
    main()