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 (1.14.1) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
)

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

var sc = bufio.NewScanner(os.Stdin)

func main() {
	// Code for C - ID
	var N, M int
	fmt.Scan(&N, &M)

	var P, Y int
	ans := make(map[int]int, M)
	year := make([]int, M)
	year1 := make([]int, M)

	city := make([]int, M)
	sc.Split(bufio.ScanWords)
	for i := 0; i < M; i++ {
		P = nextInt()
		Y = nextInt()
		ans[Y] = P
		year[i] = Y
		year1[i] = Y
		city[i] = P
	}

	ans1 := make(map[int]int, M)
	temp := make(map[int]int, M)
	sort.Sort(sort.IntSlice(year))
	for i := 0; i < M; i++ {
		temp[ans[year[i]]]++

		//fmt.Println(year[i], ans[year[i]], temp[ans[year[i]]])
		ans1[year[i]] = temp[ans[year[i]]]
	}

	for i := 0; i < M; i++ {
		fmt.Printf("%06d%06d\n", city[i], ans1[year1[i]])
	}
}