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 Go (1.6) (judge verdict: Time Limit Exceeded)

package main

import "fmt"

type City struct {
	Prefecture int
	Year       int
}

func main() {
	var N, M int
	var p, y int
	var cityID int
	fmt.Scanf("%d %d", &N, &M)
	cities := []City{}
	city := City{}

	for k := 0; k < M; k++ {
		fmt.Scanf("%d %d", &p, &y)
		city.Prefecture = p
		city.Year = y
		cities = append(cities, city)
		// 一旦全部なめる。

	}
	for k := 0; k < M; k++ {
		cityID = 1
		for kk := 0; kk < M; kk++ {
			// k市がkk県に属する場合、自分より若い市があれば追番を加算する。
			if cities[k].Prefecture == cities[kk].Prefecture {
				if cities[k].Year > cities[kk].Year {
					cityID++
				}
			}
		}
		fmt.Printf("%06d%06d\n", cities[k].Prefecture, cityID)
	}
}