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>
#include <string.h>

#define MAX 100010

void set(int **, int **,int );
void sort(int **, int *, int ,int );
int compare_int(const void* a, const void* b)
{
	return *(int*)a - *(int*)b;
}

int main()
{
	int n, m;
	int p, y;
	int **data;
	int **sdata;
	int number[MAX] = { 0 };
	char output[6+1];

	scanf("%d %d", &n, &m);
	data = (int **)malloc(sizeof(int **) * m);
	sdata = (int**)malloc(sizeof(int **) * n);
	set(data,sdata,m);

	for (int i = 0; i < m; i++) {
		scanf("%d %d", &p, &y);
		data[i][0] = p;
		data[i][1] = y;
		sdata[p - 1][number[p - 1]] = y;
		number[p - 1]++;
	}

	sort(sdata, number, n, m);

	for (int i = 0; i < m; i++) {
		sprintf(output, "%06d", data[i][0]);
		printf("%s", output);
		for (int j = 0; j < number[data[i][0] - 1]; j++) {
			if (data[i][1] == sdata[data[i][0] - 1][j]) {
				sprintf(output, "%06d",j+1);
				printf("%s\n", output);
				break;
			}
		}
	}


	/*for (int i = 0; i < m; i++) {
		free(data[i]);
		free(sdata[i]);
	}
	free(data);
	//free(sdata);
	*/
	return 0;
}

void set(int **data,int **sdata, int m)
{
	for (int i = 0; i < m; i++) {
		data[i] = (int *)malloc(sizeof(int *) * 3);
		sdata[i] = (int *)malloc(sizeof(int *) * m);
	}
}

void sort(int **sdata, int *number, int n, int m)
{
	for (int i = 0; i < n; i++) {
		qsort(sdata[i], number[i], sizeof(int), compare_int);
	}
}

/*for (int i = 0; i < n; i++) {
		for (int j = 0; j < number[i]; j++)
			printf("%d ", data[i][j]);
		printf("\n");
	}
	*/