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: Wrong Answer)

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

typedef struct {
	int p;
	int year;
	int no;
} city_data_t;

city_data_t data[100001] = {0};

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

int sort_inc_year(const void *a, const void *b)
{
	int dta = ((city_data_t*)a)->year;
	int dtb = ((city_data_t*)b)->year;
	//printf("%llu %llu\n",dta, dtb);
	return (dta - dtb);
}

int sort_inc_no(const void *a, const void *b)
{
	int dta = ((city_data_t*)a)->no;
	int dtb = ((city_data_t*)b)->no;
	//printf("%d %d\n",dta, dtb);
	return (dta - dtb);
}

int sort_inc_pref(const void *a, const void *b)
{
	int dta = ((city_data_t*)a)->p;
	int dtb = ((city_data_t*)b)->p;
	//printf("%d %d\n",dta, dtb);
	if (dta == dtb) {
		dta = ((city_data_t*)a)->year;
		dtb = ((city_data_t*)b)->year;
	}
	return (dta - dtb);
}

void printdata(int m)
{
	int i = 0;
	for(i = 0; i < m; i++) {
		printf("p=%d,y=%llu,n=%d\n", data[i].p, data[i].year, data[i].no);
	}
}

int main()
{
	int n_pref = 0;
	int m_city = 0;
	int i = 0;
	int v = 1;
	int pref_no = 0;
	scanf("%d %d", &n_pref, &m_city);
	for(i = 0; i < m_city; i++) {
		int a = 0;
		int b = 0;
		scanf("%d %d", &a, &b);
		data[i].p = a;
		data[i].year = b;
		data[i].no = i;
	}
	qsort(data, m_city, sizeof(city_data_t), sort_inc_year);
	//printdata(m_city);
	qsort(data, m_city, sizeof(city_data_t), sort_inc_pref);
	//printdata(m_city);
	for(i = 0; i < m_city; i++) {
		if(pref_no == 0) {
			pref_no = data[i].p;
		}
		if(pref_no != data[i].p) {
			v = 1;
			pref_no++;
		}
		data[i].year = v;
		v++;
	}
	qsort(data, m_city, sizeof(city_data_t), sort_inc_no);
	//printdata(m_city);
	for(i = 0; i < m_city; i++) {
		printf("%06d%06d\n",data[i].p,data[i].year);
	}
	return 0;
}