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>
#define MAX 100000

int list[MAX][3];

int com(const void *a, const void *b){
  return list[*(int*)a][1] - list[*(int*)b][1];
}

int main(){
  int n,m,
      i,
      t[MAX],
      rank[MAX];
  
  scanf("%d%d", &n, &m);
  
  for(i=0;i<m;i++){
    scanf("%d%d", &list[i][0], &list[i][1]);
    list[i][2] = 0;
  }
  for(i=0;i<m;i++){t[i]=i;}
  for(i=0;i<MAX;i++){rank[i]=0;}
  
  qsort(t,m,sizeof(int),com);
  for(i=0;i<m;i++){
    rank[list[t[i]][0]]++;
    list[t[i]][2] = rank[list[t[i]][0]];
  }
  
  for(i=0;i<m;i++){
    printf("%06d%06d\n", list[i][0], list[i][2]);
  }
  
  return 0;
}