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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Comparator;
import java.util.StringTokenizer;

public class Main {
	
	static int N,M;
	static int[][] cityArr;

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
//		long startTime = new Date().getTime();
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		N = Integer.valueOf(st.nextToken());
		M = Integer.valueOf(st.nextToken());
		
		cityArr = new int[M][4];
		
		for(int i=0;i<M;i++) {
			st = new StringTokenizer(br.readLine());
			int xq =  Integer.valueOf(st.nextToken());
			int year =  Integer.valueOf(st.nextToken());
			cityArr[i][0] = xq;//区域
			cityArr[i][1] = year;//年
			cityArr[i][2] = i;//序号
		}
		//sort
		Arrays.sort(cityArr, new Comparator<int []>() {

			@Override
			public int compare(int[] o1, int[] o2) {
				// TODO Auto-generated method stub
				if(o1[0]>o2[0]) {
					return 1;
				}else if(o1[0] == o2[0]){
					if(o1[1]>o2[1]) {
						return 1;
					}else{
						return -1;
					}
				}else {
					return -1;
				}
			}
		});
		int startt = 1;
		for(int i=0;i<M;i++) {
			if(i>0 && cityArr[i][0] != cityArr[i-1][0]) {
				startt = 1;
			}
			cityArr[i][3]=startt++;
		}
		
		//sort
		Arrays.sort(cityArr, new Comparator<int []>() {
			@Override
			public int compare(int[] o1, int[] o2) {
				// TODO Auto-generated method stub
				if(o1[2]>o2[2]) {
					return 1;
				}else{
					return -1;
				}
			}
		});

//		for(int i=0;i<M;i++) {
//			System.out.println(cityArr[i][0]+" - "+cityArr[i][1]+" - "+cityArr[i][2]+" - "+cityArr[i][3]);
//		}
		
		for(int i=0;i<M;i++) {
			System.out.format("%06d%06d\n", cityArr[i][0],cityArr[i][3]);
		}
		
		
//		long endTime = new Date().getTime();
//		System.out.println(endTime-startTime);
		
	}
	
}