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: Time Limit Exceeded)

import java.util.*;
import java.util.stream.*;
import java.util.function.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();// 県数
        int m = sc.nextInt();// 市数計
        // int[] p = new int[m];// 県番号
        // int[] y = new int[m];// 年
        int[][] py = new int[m][2];//0:元の順, 1:県, 2:年
        for(int i = 0; i < m; i++) {
            // py[i][0] = i;
            py[i][0] = Integer.parseInt(sc.next());
            py[i][1] = Integer.parseInt(sc.next());
            // p[i] = Integer.parseInt(sc.next());
            // y[i] = Integer.parseInt(sc.next());
        }
        
        // 年でソートして各県に割り振っていくのが一番無駄はない
        int[] ps = Stream.of(py).mapToInt(e -> e[0]).distinct().toArray();
        Map<Integer, List<Integer>> pyMap = new HashMap<>();
        for(int pp: ps) {
            pyMap.put(pp, new ArrayList<>());
        }
        
        // int[] sortedp = Arrays.copyOf(p, p.length);
        // Arrays.sort();
        // Arrays.sort(py, Comparator.comparingInt(e -> e[1]).thenComparing(Comparator.comparingInt(e -> e[2])));
        // 年だけでいい
        int[][] sortedPy = Arrays.copyOf(py, py.length);
        Arrays.sort(sortedPy, Comparator.comparingInt(e -> e[1]));
        for(int i = 0; i < m; i++) {
            List<Integer> ys = pyMap.get(sortedPy[i][0]);
            ys.add(sortedPy[i][1]);
        }
        
        // pyMap.values().forEach(l -> l.sort(null));

        for(int i = 0; i < m; i++) {
            int index = pyMap.get(py[i][0]).indexOf(py[i][1]);
            System.out.printf("%06d%06d%n", py[i][0], index + 1);
        }
        
    }
}