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.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class Main {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] str = br.readLine().split(" ");
		int m = Integer.parseInt(str[1]);
		List<String> list = new ArrayList<String>();
		Map<Integer, List<Integer>> map = new HashMap<Integer, List<Integer>>();
		while (m > 0) {
			String r = br.readLine();
			list.add(r);
			String[] row = r.split(" ");
			int p = Integer.parseInt(row[0]);
			int y = Integer.parseInt(row[1]);
			if (map.containsKey(p)) {
				map.get(p).add(y);
			} else {
				List<Integer> l = new ArrayList<Integer>();
				l.add(y);
				map.put(p, l);
			}
			m--;
		}
		Map<Integer, Map<Integer, Integer>> nm = new HashMap<Integer, Map<Integer, Integer>>();
		for (Entry<Integer, List<Integer>> en : map.entrySet()) {
			int key = en.getKey();
			List<Integer> value = en.getValue();
			Collections.sort(value);
			Map<Integer, Integer> subm = new HashMap<Integer, Integer>();
			for (int i = 1; i < value.size() + 1; i++) {
				subm.put(value.get(i - 1), i);
			}
			nm.put(key, subm);
		}
		for (String r : list) {
			String[] row = r.split(" ");
			int p = Integer.parseInt(row[0]);
			int y = Integer.parseInt(row[1]);
			int num = nm.get(p).get(y);
			String str1 = "000000" + p;
			String font = str1.substring(str1.length() - 6);
			String str2 = "000000" + num;
			String end = str2.substring(str2.length() - 6);
			System.out.println(font + end);
		}
	}
}