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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;
import java.awt.*;
import static java.lang.System.*;
import static java.lang.Math.*;
//Loopで使う文字列の長さは固定！
//intで大丈夫？オーバーフローしない？
//Loop回数は本当に10⁹以内になってる？Loopは回る？？
public class Main {
    public static void main(String[]$){
        Scanner sc = new Scanner(in);
        int n=sc.nextInt();
        int m=sc.nextInt();
        int[] p=new int[m];
        int[] y=new int[m];
        HashMap<Integer,Integer> map=new HashMap<>();
        HashMap<Integer,Integer> YtoM=new HashMap<>();
        TreeMap<Integer,Integer> tm=new TreeMap<>();
        for (int i = 0; i < m; i++) {
            p[i]=sc.nextInt();
            y[i]=sc.nextInt();
            tm.put(y[i],p[i]);
            map.put(p[i],1);
            YtoM.put(y[i],i);
        }
        String[] ans=new String[m];
        for(int k:tm.keySet()){
            String left="";
            String right="";
            left=Integer.toString(tm.get(k));
            int length=left.length();
            for (int i = 0; i <6-length; i++) {
                left="0"+left;
            }
            right=Integer.toString(map.get(tm.get(k)));
            length=right.length();
            for (int i = 0; i <6-length; i++) {
                right="0"+right;
            }
            map.put(tm.get(k),map.get(tm.get(k))+1);
            ans[YtoM.get(k)]=left+right;
        }
        for (int i = 0; i < m; i++) {
            out.println(ans[i]);
        }
    }
}