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 Ruby (2.3.3) (judge verdict: Accepted)

pamox, camo = gets.split.map(&:to_i)
cities = camo.times.map{gets.split.map(&:to_i)}

prefs = Hash.new

index = 0
cities.each do |city|
  prefs[city[0]] = [] if prefs[city[0]] == nil
  prefs[city[0]].push([index, city[1]])
  index += 1
end

res = []

prefs.values.each do |pref|
  pref.sort_by!{|value| value[1]}
end

prefs.each do |prefW|
  count = 1
  prefW[1].each do |city|
    res.push([city[0], prefW[0], count])
    count += 1
  end
end

res.sort_by!{|v| v[0]}

final = []
res.each do |resval|
  final.push(format("%06d", resval[1]) + format("%06d", resval[2]))
end

puts final