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 (2.7.1) (judge verdict: Wrong Answer)

n,m = gets.strip.split.map(&:to_i)
pref = Array.new(n){Array.new}
i = 1
while i <= m do
  p,y = gets.strip.split.map(&:to_i)
  pref[p-1] << [i,y].to_a  #[市の番号,誕生年]
  i += 1
end
#すべて入力完了
#全ての配列を年代順にソート
city = Array.new(m)
j = 0
while j < n do
  unless pref[j] == nil
    pref[j].sort_by {|x| x[1]}
    k = 0
    while k < pref[j].size do
      city[pref[j][k][0]-1] = ('%012d' % ((j+1)*(10**6)+(k+1)))
      k += 1
    end
  end
  j += 1
end
m.times do |d|
  puts city[d]
end