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 PyPy3 (2.4.0) (judge verdict: Accepted)

import sys

# import bisect
# from collections import Counter, deque, defaultdict

# import copy
# from heapq import heappush, heappop, heapify
# from fractions import gcd
# import itertools
from operator import attrgetter, itemgetter

# import math

# import numpy as np

readline = sys.stdin.readline
MOD = 10 ** 9 + 7
INF = float('INF')
sys.setrecursionlimit(10 ** 5)


def main():
    n, m = list(map(int, readline().split()))
    pyir = [[0] * 4 for _ in range(m)]

    for i in range(m):
        p, y = list(map(int, readline().split()))
        pyir[i][0] = p
        pyir[i][1] = y
        pyir[i][2] = i

    pyir.sort(key=itemgetter(0,1))

    x = 0
    pprev = pyir[0][0]

    for i in range(m):
        if pprev != pyir[i][0]:
            x = 0
        x += 1
        pyir[i][3] = str(pyir[i][0]).zfill(6) + str(x).zfill(6)
        pprev = pyir[i][0]

    pyir.sort(key=itemgetter(2))

    for i in range(m):
        print(pyir[i][3])

if __name__ == '__main__':
    main()