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)

log = console.log;

var stdin = require("fs").readFileSync("/dev/stdin", "UTF-8");
var lines = stdin.split("\n");
var N = Number(lines[0].split(" ")[0]);
var M = Number(lines[0].split(" ")[1]);
lines = lines.splice(1).filter(v => v !== "");
cities = lines.map((v, i) => {
  P = Number(v.split(" ")[0]);
  Y = Number(v.split(" ")[1]);

  return {
    cityIndex: i,
    prefecture: P,
    year: Y
  };
});

cities.sort((a, b) => {
  return a.year - b.year;
});

count = [];

cities = cities.map(c => {
  count[c.prefecture] === undefined
    ? (count[c.prefecture] = 1)
    : (count[c.prefecture] += 1);

  P = "000000" + c.prefecture.toString();
  P = P.substr(P.length - 6, 6);
  id = "000000" + count[c.prefecture].toString();
  id = id.substr(id.length - 6, 6);

  return {
    cityIndex: c.cityIndex,
    prefecture: P,
    year: Y,
    id: id
  };
});

cities.sort((a, b) => {
  return a.cityIndex - b.cityIndex;
});

cities.forEach(c => console.log(c.prefecture.toString() + c.id.toString()));