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)

function zeroPadding(str) {
  return ('000000' + str).slice(-6)
}


function Main(input) {
  const data = input.trim().split('\n')
  const temp = data[0].split(' ').map(s => parseInt(s))
  const N = temp[0] // 県
  const M = temp[1] // 市

  const rest = data.slice(1).map(s => {
    return s.split(' ').map(x => parseInt(x))
  })

  var ans = {}
  rest.forEach((d, index) => {
    if(!ans[d[0]]) ans[d[0]] = []
    ans[d[0]].push({index: index, p: d[0], t: d[1], s: '' })
  })

  // console.log(ans)


  for(var i in ans) {
    ans[i] = ans[i].sort((a, b) => a.t - b.t)
  }

  var res = Array(M)
  for(var i in ans) {
    for(var j = 0; j < ans[i].length; ++j) {
      var d = ans[i][j]
      var str = zeroPadding(d.p) + zeroPadding((j+1).toString())
      res[d.index] = str
    }
  }

  var output = res.reduce((p, c) => p + '\n' + c)

  console.log(output)
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));