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 compare_int(const void *a, const void *b){
    return *(int *)a - *(int *)b;
}

int search_int(int key, int n, int yd[]){
    int high=n-1,low=0,mid;
    while(low <= high){
        mid=(low + high)/2;
        if(yd[mid]==key){
            return mid;
        }else if(yd[mid]>key){
            high = mid-1;
        }else{
            low = mid+1;
        }
    }
    return -1;
}

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

int main(void){
    int n,m,i,j,k,count[100001]={0};
    scanf("%d %d",&n,&m);
    city data[m];
    for(i=0;i<m;i++){
        scanf("%d %d",&data[i].p,&data[i].year);
        count[data[i].p]++;
    }
    int yd[m];
    for(i=1;i<n+1;i++){
        k=0;
        for(j=0;j<m;j++){
            if(data[j].p==i){
                yd[k++]=data[j].year;
            }
        }
        qsort(yd,k,sizeof(int),compare_int);
        for(j=0;j<m;j++){
            if(data[j].p==i){
                data[j].rank=1+search_int(data[j].year,k,yd);
            }
        }
    }
    for(i=0;i<m;i++){
        printf("%012d\n", 1000000*data[i].p+data[i].rank);
    }
    return 0;
}