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: Accepted)

#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <math.h>

#define P 1000000007

int comp(const void *a, const void *b){return *(int*)a-*(int*)b;}
int compw(const void *a, const void *b){return (*(int*)a>*(int*)b)-(*(int*)a<*(int*)b);}
int compu(const void *a, const void *b){
	if(*((int*)a+1)==*((int*)b+1)){
		return *((int*)a+2)-*((int*)b+2);
	}else{
		return *((int*)a+1)-*((int*)b+1);
	}
}

uint32_t nextpint(void){
	uint_fast32_t x=0;
	while(1){
		uint_fast8_t c=getchar();
		if('0'<=c && c<='9'){
			x=x*10+c-'0';
		}else{
			break;
		}
	}
	return x;
}

int data[100000][4];
int main(void){
	int n = nextpint();
	int m = nextpint();
	for(int i=0; i<m; i++){
		data[i][0] = i;
		data[i][1] = nextpint();
		data[i][2] = nextpint();
		data[i][3] = 0;
	}
	qsort(data, m, sizeof(int)*4, compu);
	int a = 0;
	int b = 0;
	for(int i=0; i<m; i++){
		if(data[i][1] != a){
			a = data[i][1];
			b = 0;
		}
		data[i][3] = ++b;
	}
	qsort(data, m, sizeof(int)*4, comp);
	for(int i=0; i<m; i++){
		printf("%06d%06d\n", data[i][1], data[i][3]);
	}
}