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.*;
public class Main {
	Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		new Main().doIt();
	}
	void doIt() {
		abc113c();
	}
	void abc113c() {
		int N = sc.nextInt(), M = sc.nextInt();
		Record [] data = new Record[M+1];
		String [] ans = new String[M];
		data[0] = new Record(-1, -1, -1);
		for(int i = 0; i < M; i++) {
			int p = sc.nextInt(), y = sc.nextInt();
			data[i+1] = new Record(p, y, i);
		}
		Arrays.sort(data);
		int nth = 1;
		for(int i = 1; i <= M; i++) {
			if(data[i-1].preference != data[i].preference) {
				nth = 1;
			} else nth++;
			ans[data[i].id] = String.format("%06d%06d", data[i].preference, nth);
		}
		for(int i = 0; i < M; i++) {
			System.out.println(ans[i]);
		}
	}
	class Record implements Comparable<Record> {
		Record(int p, int y, int id) {
			this.preference = p;
			this.year = y;
			this.id = id;
		}
		int preference, year, id;
		public int compareTo(Record o) {
			if(preference != o.preference) {
				return preference - o.preference;
			} else if (year != o.year) {
				return year - o.year;
			} else {
				return id - o.id;
			}
		}
	}
}