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 static java.lang.Integer.*;
//import static java.lang.Long.*;
//import static java.lang.Math.*;
import static java.lang.System.*;

import java.io.PrintWriter;

public class Main {
	public static void main(String[] args) {
		int i, j, k;
		Scanner sc = new Scanner(System.in);
		int n = parseInt(sc.next());
		int m = parseInt(sc.next());
		Py[] py = new Py[m];
		int[] p = new int[m];
		for(i = 0; i < m; i++) {
			p[i] = parseInt(sc.next());  
			py[i] = new Py(i, p[i],parseInt(sc.next()));
		}
		sc.close();
		Arrays.sort(py, (a, b) -> {if(a.p != b.p) {
			return a.p - b.p;
		} else {
			return a.y - b.y;
		}
		});
		int prep = -1;
		int xx = 0;
		int[] x = new int[m];
		for(i = 0; i < m; i++) {
			if(prep == py[i].p) {
				xx++;
			} else {
				prep = py[i].p;
				xx=1;
			}
			x[py[i].m] = xx;
		}
//		Arrays.sort(py, (a, b) -> a.m - b.m);
		PrintWriter out = new PrintWriter(System.out);
		for(i = 0; i < m; i++) {
			out.printf("%06d%06d%n", p[i], x[i]);
		}
		out.flush();
	}
}
class Py {
	int p;
	int y;
	int m;
	Py(int m, int p, int y){
		this.m = m;
		this.p = p;
		this.y = y;
	}
}