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 main = arg => {
    arg = arg.trim().split("\n");
    const N = parseInt(arg[0].split(" ")[0]);
    const M = parseInt(arg[0].split(" ")[1]);

    const PY = arg.slice(1, M + 1).map(n=>n.split(" ").map(l=>parseInt(l)));
    const list = [];
    
    for(let i in PY) {
        let map = {p: PY[i][0], y: PY[i][1], originIdx: i};
        
        list.push(map);
    }
    
    // PY.sort((a,b)=> (a[0] - b[0]) || (a[1] - b[1]));
    list.sort((a,b)=> (a.p - b.p) || (a.y - b.y));
    
    const addZero = n => {
        const zeros = [];
        
        for(let i=0; i<6 - String(n).length; i++) {
            zeros.push("0");
        }
        
        return zeros.join("") + String(n);
    }
    
    let temp = [];
    let oldness = 1;
    
    for(let i in list) {
        if(list[i-1] && list[i-1].p !== list[i].p) {
            oldness = 1;
        }
        
        let first = addZero(list[i].p);
        let last  = addZero(oldness);
        
        let map = {id: first + last, originIdx: list[i].originIdx}
        
        temp.push(map);
        oldness++;
    }
    
    // console.log(PY.join("\n"));
    // console.log(addZero(3));
    
    temp.sort((a,b)=>a.originIdx - b.originIdx);
    
    let answer = [];
    
    for(let i in temp) {
        answer.push(temp[i].id);
    }
    
    console.log(answer.join("\n"));
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));