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

class City:
    def __init__(self, i1, p, y, o=None):
        self.i1 = i1
        self.p = p
        self.y = y
        self.o = o

    # def __repr__(self):
    #     return f"City({self.i1}, {self.p}, {self.y}, {self.o})"

    def get_id(self):
        return "%06d%06d" % (self.p, self.o)

def put_ids(n, cities):
    years = {i: [] for i in range(1, n + 1)}
    for c in cities:
        years[c.p].append(c.y)

    year_to_order = {i: {} for i in range(1, n + 1)}
    for i in range(1, n + 1):
        ys = sorted(years[i])
        for j0, y in enumerate(ys):
            year_to_order[i][y] = j0 + 1

    for c in cities:
        c.o = year_to_order[c.p][c.y]

def main():
    n, m = map(int, input().split())
    cities = []
    for i0 in range(m):
        p, y = map(int, input().split())
        city = City(i0, p, y)
        cities.append(city)
    put_ids(n, cities)
    for c in cities:
        print(c.get_id())

main()