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

var sc = bufio.NewScanner(os.Stdin)

func stringLineScan() string {
	sc.Scan()
	return sc.Text()
}

func main() {
	sc.Split(bufio.ScanWords)
	_, _ = strconv.Atoi(stringLineScan())
	m, _ := strconv.Atoi(stringLineScan())
	py := make([][]int, m)
	x := map[int][]int{}
	for i := 0; i < m; i++ {
		t := make([]int, 2)
		t[0], _ = strconv.Atoi(stringLineScan())
		t[1], _ = strconv.Atoi(stringLineScan())
		py[i] = t
		if val, ok := x[t[0]]; ok {
			x[t[0]] = append(val, t[1])
		} else {
			u := make([]int, 1)
			u[0] = t[1]
			x[t[0]] = u
		}
	}
	for k, _ := range x {
		sort.Ints(x[k])
	}
	y := map[string]string{}
	for k, v := range x {
		for i, w := range v {
			q := make([]int, 2)
			q[0], q[1] = k, w
			y[fmt.Sprint(q)] = fmt.Sprintf("%06d", k) + fmt.Sprintf("%06d", i+1)
		}
	}
	for _, b := range py {
		fmt.Println(y[fmt.Sprint(b)])
	}
}