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)

def convert_citynum(pref_num, rank)
  s_pref_num = pref_num.to_s
  s_rank = rank.to_s
  while s_pref_num.length != 6
    s_pref_num = "0" + s_pref_num
  end
  while s_rank.length != 6
    s_rank = "0" + s_rank
  end
  return s_pref_num + s_rank
end
n, m = gets.chomp!.split(' ').map(&:to_i)
data = {}
n.times do |i|
  data[i+1] = []
end
m.times do |i|
  p, y = gets.chomp!.split(' ').map(&:to_i)
  data[p] << [i+1, y]
end
result = []
data.each do |p_num, val|
  val.sort!{ |cur, nxt| cur[1] <=> nxt[1] }
  i = 0
  val = val.map do |id, year|
    i += 1
    [id, convert_citynum(p_num, i)]
  end
  result << val
end
result.flatten!(1)
result.sort!{ |cur, nxt| cur[0] <=> nxt[0] }
result.each do |val|
  puts val[1]
end