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)

num_of_prefectures, cities = gets.split.map &:to_i

history = Array.new(num_of_prefectures, 0)

#ans[n][0]: prefecture,          ans[n][1]: year
#ans[n][2]: i (ith information), ans[n][3]: j (jth city)
ans = Array.new(cities).map{Array.new(4, 0)}

cities.times do |i|

  prefecture, year = gets.split.map &:to_i

  ans[i][0] = "%06d" % prefecture
  ans[i][1] = year
  ans[i][2] = i

end

#Sort by year
ans = ans.sort_by { |a| a[1] }

cities.times do|i|

  ans[i][3] = "%06d" % (history[ans[i][0].to_i - 1] + 1)
  history[ans[i][0].to_i - 1] += 1

end

ans = ans.sort_by { |e| e[2] }

ans.each{ |c| puts [c[0], c[3]].join }