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 (Clang 3.8.0) (judge verdict: Runtime Error)

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

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


int main(void)
{
	int n, m, i, k, t;
	int a[100000], b[100000], c[100000][100000];
	scanf("%d %d", &n, &m);
	for (i = 0; i < m; i++)
	{
		scanf("%d %d", &a[i], &b[i]);
	}
	for (i = 0; i < n; i++)
	{
		t = 0;
		for (k = 0; k < m; k++)
		{
			if (a[k] == i)
			{
				c[i][t] = b[k];
				t++;
			}
		}
		qsort(c[i], t + 1, sizeof(int), compare_int);
	}

	for (i = 0; i < m; i++)
	{
		for (k = 0; k < n; k++)
		{
			if (a[i] == k)
			{
				for (t = 0; t < m; t++)
				{
					if (b[i] == c[k][t])
					{
						printf("%06d", a[i]);
						printf("%06d", t);
						break;
					}
				}
				break;
			}
		}
	}

	return 0;
}