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 C (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>
#include <stdlib.h>

typedef struct{
	int p;
	int y;
	int order;
}DATA;

typedef struct{
	DATA* data;
	int y;
	int order;
}P_DATA;
 
int cmp( const void *p, const void *q ) {
    return ((P_DATA*)p)->y - ((P_DATA*)q)->y;
}
 
int main(void){
	
	int i, j, n, m, ptr;
	
	scanf("%d %d", &n, &m);
	
	int p_cnt[n + 1];
	for(i = 0; i <= n; i++){
		p_cnt[i] = 0;
	}
	
	DATA data[m];
	P_DATA p_data[n + 1][m];
	
	for(i = 0; i < m; i++){
		scanf("%d %d", &data[i].p, &data[i].y);
		p_data[data[i].p][p_cnt[data[i].p]].data = &data[i];
		p_data[data[i].p][p_cnt[data[i].p]].y = data[i].y;
		p_cnt[data[i].p]++;
	}
	
	for(i = 1; i <= n; i++){	// iは県番号
		if(p_cnt[i] > 0){
			
			qsort(p_data[i], p_cnt[i], sizeof(P_DATA), cmp);
			
			for(j = 0; j < p_cnt[i]; j++){
				p_data[i][j].order = j + 1;
				(p_data[i][j].data)->order = j + 1;
			}
			
		}
	}
	
	for(i = 0; i < m; i++){
		printf("%012d\n", data[i].p * 1000000 + data[i].order);
	}
	
	
	
	return 0;
}