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.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

import static java.lang.Integer.parseInt;

public class Main {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] padding = new String[]{"", "0", "00", "000", "0000", "00000"};
        StringTokenizer st = new StringTokenizer(br.readLine());
        int N = parseInt(st.nextToken());
        int M = parseInt(st.nextToken());
        int[][] cities = new int[M][4];//[p,y,index,sort]

        for (int i = 0; i < M; i++) {
            st = new StringTokenizer(br.readLine());
            cities[i][0] = parseInt(st.nextToken());
            cities[i][1] = parseInt(st.nextToken());
            cities[i][2] = i;
        }
        br.close();

        Arrays.sort(cities, (e1, e2) -> (e1[0] == e2[0]) ? (e1[1] - e2[1]) : (e1[0] - e2[0]));
        cities[0][3] = 1;
        for (int i = 1; i < M; i++) {
            cities[i][3] = (cities[i][0] == cities[i - 1][0]) ? cities[i - 1][3] + 1 : 1;
        }

        Arrays.sort(cities, (e1, e2) -> e1[2] - e2[2]);
        StringBuilder sb = new StringBuilder(100000 * 13);

        for (int[] city : cities) {
            sb.append(padding[getZeroCnt(city[0])]).append(city[0]);
            sb.append(padding[getZeroCnt(city[3])]).append(city[3]).append('\n');
        }
        System.out.println(sb.toString());
    }

    private static int getZeroCnt(int n) {
        if (n < 10) return 5;
        else if (n < 100) return 4;
        else if (n < 1000) return 3;
        else if (n < 10000) return 2;
        else if (n < 100000) return 1;
        else return 0;
    }
}