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)

"use strict";

    
const make6digit = num => {
    num = String(num);
    let digit = num.split("").length;
    
    if(digit < 6) {
        for(let i=0; i<6-digit; i++) {
            num = "0" + num;
        }
    }
    
    return num;
}

const main = arg => {
    arg = arg.trim().split("\n");
    const N = parseInt(arg[0].split(" ")[0]);
    const M = parseInt(arg[0].split(" ")[1]);
    
    const cities = arg.slice(1, M + 1);
    let data = [];
    
    for(let i in cities) {
        let tempPrefecture = parseInt(cities[i].split(" ")[0]);
        let tempBirth      = parseInt(cities[i].split(" ")[1]);
        
        data.push({
            prefecture: tempPrefecture,
            birth:      tempBirth,
            index:      i
        })
    }
    
    data.sort((a,b) => {
        if(a.prefecture < b.prefecture) {
            return -1;
        }
        
        if(a.prefecture > b.prefecture) {
            return 1;
        }
        
        if(a.birth < b.birth) {
            return -1;
        }
        
        if(a.birth > b.birth) {
            return 1;
        }
    });
    
    let num = 1;
    
    for(let i in data) {
        if(data[i-1]) {
            if(data[i].prefecture !== data[i-1].prefecture) {
                num = 1;
            }
        }
        
        let firstHalf = make6digit(data[i].prefecture);
        let lastHalf  = make6digit(num);
        
        const id = firstHalf + lastHalf;
        
        data[i].id = id;
        
        num++;
    }
    
    data.sort((a,b)=>a.index - b.index);
    
    for(let i in data) {
        console.log(data[i].id);   
    }
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));