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.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try {
            StringTokenizer st = new StringTokenizer(br.readLine());
            int N = Integer.valueOf(st.nextToken());
            int M = Integer.valueOf(st.nextToken());
            Map<String, String> map = new HashMap<String, String>();
            String[][] data = new String[M][2];
            String[] a = new String[M];
            for (int i = 0; i < M; i++) {
                st = new StringTokenizer(br.readLine());
                String p = st.nextToken();
                String y = st.nextToken();

                String p0 = "000000" + p;
                String y0 = "000000000" + y;

                String tempp = p0.substring(p0.length() - 6, p0.length());
                String tempy = y0.substring(y0.length() - 10, y0.length());
                data[i][0] = tempp;
                data[i][1] = tempy;
                a[i] = tempp + "_" + tempy;
            }
            Arrays.sort(a);
            int index = 1;
            String t = a[0].split("_")[0];
            for (int i = 0; i < M; i++) {
                String[] temps = a[i].split("_");
                if (t.equals(temps[0])) {
                    map.put(a[i], "" + index);
                    index++;
                } else {
                    t = temps[0];
                    index = 1;
                    map.put(a[i], "" + index);
                    index++;
                }
            }
            for (int i = 0; i < M; i++) {
                String num = map.get(data[i][0] + "_" + data[i][1]);
                num = "000000000" + num;
                num = num.substring(num.length() - 6, num.length());
                System.out.println(data[i][0] + "" + num);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

}