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>
#include<string.h>

typedef struct{
    int a;
    int p;
    int y;
    int t;
}city_s;

int citysort(const void *a, const void *b){
    int city = ((city_s*)a)->p - ((city_s*)b)->p; 
    int year = ((city_s*)a)->y - ((city_s*)b)->y;
    if(city != 0){
        return city;
    }else if(year != 0){
        return year;
    }else{
        return 0;
    }
}

int sortret(const void *A, const void *B){
    return ((city_s*)A)->a - ((city_s*)B)->a;
}

int main(){
    int N, M;
    city_s citynum[110000];
    int i, j, k;
    int tmp, citytmp;

    scanf("%d %d", &N, &M);
    for(i=0; i<M; i++){
        scanf("%d %d", &citynum[i].p, &citynum[i].y);
        citynum[i].a = i;
    }

    qsort(citynum, M, sizeof(city_s), citysort);

    j=1;
    tmp = 1;
    citytmp = 1;

    for(i=0; i<M; i++){
        if(citynum[i].p != citytmp){
            citytmp = citynum[i].p;
            tmp = 1;
        }
        citynum[i].t = tmp;
        tmp++;
    }

    qsort(citynum, M, sizeof(city_s), sortret);

    for(i=0; i<M; i++){
        printf("%012.0lf\n", (double)citynum[i].p*1000000 + citynum[i].t);
    }

    return 0;
}