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 JavaScript (node.js v5.12) (judge verdict: Accepted)

var lines = [];
var result = [];
var readline = require("readline");

var rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
});

rl.on('line', function (x) {
    lines.push(x);
});

rl.on('close', function () {
    var N = Number(lines[0].split(" ")[0]);
    var M = Number(lines[0].split(" ")[1]);

    lines.shift();

    var array = lines.map(value => value.split(" ").map(value => Number(value)));

    for (var i = 0; i < M; i++) {
        array[i].push(i);
    }

    var city = array.concat().sort((a, b) => a[1] - b[1]);
    ite = Array(N + 1).fill(0);
    for (var i = 0; i < M; i++) {
        var ken = city[i][0].toString(); var shi = (ite[city[i][0]] + 1).toString();

        len = ken.length
        for (var x = 0; x < 6 - len; x++) { ken = "0" + ken; }

        len = shi.length
        for (var x = 0; x < 6 - len; x++) { shi = "0" + shi; }

        city[i].push(ken + shi);
        ite[city[i][0]]++;
    }

    city.sort((a, b) => a[2] - b[2]);
    for (var i = 0; i < M; i++) {
        console.log(city[i][3]);
    }
});