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: Wrong Answer)

String.prototype.padStart = function padStart(targetLength, padString) {
  targetLength = targetLength >> 0; // truncate if number or convert non-number to 0;
  padString = String(typeof padString !== 'undefined' ? padString : ' ');
  if (this.length > targetLength) {
    return String(this);
  } else {
    targetLength = targetLength - this.length;
    if (targetLength > padString.length) {
      padString += padString.repeat(targetLength / padString.length); // append to original to ensure we are longer than needed
    }
    return padString.slice(0, targetLength) + String(this);
  }
};

const Main = (input) => {
  // 入力値の整形
  input = input.split('\n');
  input.shift();
  const cities = input.map((line, index) => {
    const lineArray = line.split(' ');
    const ken = lineArray[0];
    const year = lineArray[1];
    return {
      index: index,
      ken: ken,
      year: year,
    };
  });

  const kenArray = [];
  cities
    .concat()
    .sort((a, b) => {
      return a.year - b.year;
    })
    .forEach((city) => {
      if (!kenArray[city.ken]) kenArray[city.ken] = [];
      kenArray[city.ken].push(city);
      cities[city.index].cityId =
        String(city.ken).padStart(6, '0') +
        String(kenArray[city.ken].length).padStart(6, '0');
    });

  cities.forEach((city) => {
    console.log(city.cityId);
  });
};

//* この行以降は編集しないでください（標準入出力から一度に読み込み、Mainを呼び出します）
Main(require('fs').readFileSync('/dev/stdin', 'utf8'));