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: Runtime Error)

let input = require('fs').readFileSync('/dev/stdin', 'utf8').split(/\s/);

const N = Number(input[0]);
const M = Number(input[1]);
const P = input.slice(2, 2 + 2 * M).filter((_, idx) => idx % 2 === 0).map(Number);
const Y = input.slice(3, 3 + 2 * M).filter((_, idx) => idx % 2 === 0).map(Number);

let index = [...Array(M)].map((_, idx) => idx + 1)

let dataframe = {"P": P, "Y": Y, "index": index};

dataframe.sort(function(a, b){
    if (a.Y < b.Y) return -1;
    if (a.Y > b.Y) return 1;
    return 0;
});

let number = [];
let counter = [...Array(N)].map((_, idx) => 0);

for (let i = 0; i < M; i++) {
    let city_num = dataframe[i].P;
    counter[city_num] += 1;
    tmp = 1000000 * city_num + counter[city_num];
    number.push(zeroPadding(tmp, 12));
}

let dataframe_new = {"number": number, "P": dataframe.P, "Y": dataframe.Y, "index": dataframe.index}

function zeroPadding(num, length) {
    return ('00000000000' + num).slice(-length);
}

dataframe_new.sort(function(a, b){
    if (a.index < b.index) return -1;
    if (a.index > b.index) return 1;
    return 0;
});

for (let i = 0; i < M; i++) {
    console.log(dataframe_new[i].number)
}