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: Accepted)

n,m=gets.split.map &:to_i
p=[];y=[]
m.times{|i|p[i],y[i]=gets.split.map &:to_i}
ans=p.zip(y,(0..m).to_a).sort_by{|x|[x[0],x[1]]}
z=1
for i in 0...m
  (ans[i][3]=z;next) if i==0
  if ans[i-1][0]==ans[i][0]
    z+=1
    ans[i][3]=z
  else
    z=1
    ans[i][3]=z
  end
end
m.times{|i|
    x=(1000000+ans[i][0]).to_s.chars
    y=(1000000+ans[i][3]).to_s.chars
    x.shift;y.shift
    ans[i][4]=(x+y).join
}
ans=ans.sort_by{|x|x[2]}
ans.each{|y|puts y[4]}