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: Accepted)

package main

import (
	"fmt"
	"sort"
)

type DirRange []uint

func (a DirRange) Len() int           { return len(a) }
func (a DirRange) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
func (a DirRange) Less(i, j int) bool { return a[i] < a[j] }

func main() {
	var N, M uint
	fmt.Scanf("%d%d", &N, &M)
	hash := make([]uint, M)
	for i := uint(0); i < M; i++ {
		var Pi, Yi uint
		fmt.Scanf("%d%d", &Pi, &Yi)
		hash[i] = Pi*100000*1000000000 + (Yi-1)*100000 + i
	}
	sort.Sort(DirRange(hash))
	Pl := uint(0)
	count := uint(0)
	for i := uint(0); i < M; i++ {
		Pi := hash[i] / 100000 / 1000000000
		j := hash[i] % 100000
		if Pi > Pl {
			Pl = Pi
			count = 0
		}
		hash[i] = j*1000000*1000000 + Pi*1000000 + count + 1
		count++
	}
	sort.Sort(DirRange(hash))
	for i := uint(0); i < M; i++ {
		fmt.Printf("%012d\n", hash[i]%1000000000000)
	}
	return
}