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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;

public class AtCoder{
	public static void Main(){
		string[] s;
		s = Console.ReadLine().Trim().Split(' ');
		int n,m;
		n = int.Parse(s[0]);
		m = int.Parse(s[1]);
		
		int[] p = new int[m];
		int[] y = new int[m];
		int[] x = new int[m];
		int[] o = new int[m];
		for (int i = 0; i < m; i++){
			o[i] = i;
			s = Console.ReadLine().Trim().Split(' ');
			p[i] = int.Parse(s[0]);
			y[i] = int.Parse(s[1]);
			x[i] = int.Parse(s[1]);
		}
		Array.Sort(y,p);
		Array.Sort(x,o);
		int[] q = new int[m];
		for (int i = 0; i < m; i++){
			q[i] = p[i];
		}
		Array.Sort(p,y);
		Array.Sort(q,o);
		
		int c = 0;
		int r = p[0];
		long[] ans = new long[m];
		for (int i = 0; i < m; i++){
			if(r!=p[i]){
				c = 1;
				ans[o[i]] = 1 + p[i]*1000000;
			}else{
				c++;
				ans[o[i]] = c + p[i]*1000000;
			}
		}
		string t;
		for (int i = 0; i < m; i++){
			t = ans[i].ToString();
			while(t.Length<12){
				t = "0"+t;
			}
			Console.WriteLine(t);
		}
		
	}
}