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)

function main(input) {
    const args = input.split('\n')
    const args0 = args[0].split(' ')
    const sumPrefecture = +args0[0]
    const sumCity = +args0[1]
    args.shift()

    const cityList = args.map(item => {
        const tmpArry = item.split(' ')
        const belongPrefecture = tmpArry[0]
        const barthYear = tmpArry[1]
        return {pre: +belongPrefecture, year: +barthYear}
    })

    const preList = {}
    for (let i = 1; i <= sumPrefecture; i++) {
        preList[i.toString().padStart(6, '0')] = cityList.filter(item => {
            return item.pre == i
        }).map(item => {
            return item.year
        }).sort(function (a, b) {
            return a - b
        })
    }

    Object.keys(preList).forEach((key, index) => {
        for (let [item, index2] of preList[key].entries()) {
            console.log(key+(+item + 1).toString().padStart(6,'0'))
        }

    })


}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));