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

struct city{
  int num;
  int y;
  int p;
};

int city_compare(const void *a, const void *b){
  struct city *A = (struct city *)a;
  struct city *B = (struct city *)b;
  if(A->p > B->p) return 1;
  if(A->p < B->p) return -1;
  else return A->y - B->y;
}

int
main(int argc, char *argv[])
{
  int n, m; struct city c[100000];
  scanf("%d %d", &n, &m);
  for(int i = 0; i < m; i++){
    scanf("%d %d", &c[i].p, &c[i].y);
    c[i].num = i;
  }

  qsort(c, m, sizeof(struct city), city_compare);

  int k = 1, id[100000][2];
  for(int i = 0; i < m; i++){
    id[c[i].num][0] = c[i].p;
    id[c[i].num][1] = k++;
    if(c[i].p != c[i + 1].p) k = 1;
  }

  for(int i = 0; i < m; i++){
    printf("%06d%06d\n", id[i][0], id[i][1]);
  }

  return 0;
}