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>

typedef struct {
    int num;
    int p;
    int year;
    int rank;
} city;

int cmp_year(const void *p, const void *q){
    return ((city*)p)->year - ((city*)q)->year;
}

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

int main(void){
    int n,m,i,count[200000]={0};
    scanf("%d %d",&n,&m);
    city data[m];
    for(i=0;i<m;i++){
        data[i].num=i;
        scanf("%d %d",&data[i].p, &data[i].year);
    }
    qsort(data, m, sizeof(city), cmp_year);
    for(i=0;i<m;i++){
        data[i].rank=(count[data[i].p]++)+1;
    }
    qsort(data, m, sizeof(city), cmp_num);
    for(i=0;i<m;i++){
        printf("%012d\n", 1000000*data[i].p+data[i].rank);
    }
    return 0;
}