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>
int func(const void* a,const void* b);
typedef struct {
    int year_of_birth;
    int prefecture;
    int number;
    unsigned long int ans;
}city;

int main(){
    int n,m;
    scanf("%d %d",&n,&m);

    int prefecture_ptr[n];
    for(int i = 0;i < n;i++){
        prefecture_ptr[i] = 0;
    }

    city towns[m];
    for(int i = 0;i < m;i++){
        scanf("%d %d",&towns[i].prefecture,&towns[i].year_of_birth);
        towns[i].number = i;
        towns[i].ans = 0;
    }
    
    qsort(towns,m,sizeof(city),func);
    
    for(int i = 0;i < m;i++){
        towns[i].ans = ++prefecture_ptr[towns[i].prefecture - 1];
        //printf("%d\n", ++prefecture_ptr[towns[i].prefecture - 1]);
        towns[i].ans += towns[i].prefecture * 1000000;
    }

    unsigned long int ans_num[m];
    for(int i = 0;i < m;i++){
        int hoge = towns[i].number;
        ans_num[hoge] = towns[i].ans;
    }
    for(int i = 0;i < m;i++){
        printf("%012lu\n",ans_num[i]);
    }
    return 0;
}
int func(const void* a,const void* b){
    return ((city*)a)->year_of_birth - ((city*)b)->year_of_birth;
}