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 <math.h>

typedef struct {
  int num;
  int P;
  long long int Y;
  int y;
} bigint;

int cmp( const void *p, const void *q ) {
  if(((bigint*)p)->Y - ((bigint*)q)->Y > 0){
    return 1;
  }else{
    return -1;
  }
}

int cmp2( const void *p, const void *q ) {
    return ((bigint*)p)->num - ((bigint*)q)->num;
}

void sixint(int N){
  int i;
  int k[6];

  for(i=5;i>=0;i--){
    k[i]=(int)(N/pow(10,5-i));
    N=(int)N/10;
  }
  
  for(i=0;i<6;i++){
    printf("%d",k[i]);
  }
}

int main(){
  int N,M,i;
  scanf("%d%d",&N,&M);
  bigint X[M];
  for(i=0;i<M;i++){
    scanf("%d%lld",&X[i].P,&X[i].Y);
    X[i].num=i;
  }
  qsort(X, M, sizeof(bigint), cmp);
  int c_P[N+1];
  for(i=0;i<N+1;i++){
    c_P[i]=1;
  }
  for(i=0;i<M;i++){
    X[i].y = c_P[X[i].P];
    c_P[X[i].P]=c_P[X[i].P]+1;
  }
  qsort(X, M, sizeof(bigint), cmp2 );
  for(i=0;i<M;i++){
    sixint(X[i].P);
    sixint(X[i].y);
    printf("\n");
  }
  return 0;
}