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 node{
    int id;
    int p;
    int y;
}node;

int cmp1(const void* a, const void* b){
    if(((node*)a)->p == ((node*)b)->p){
        return ((node*)a)->y - ((node*)b)->y;
    }
    return ((node*)a)->p - ((node*)b)->p;
}

int cmp2(const void* a, const void* b){
    return ((node*)a)->id - ((node*)b)->id;
}

int main(){
    int n, m;
    scanf("%d %d", &n, &m);
    node a[m];
    for(int i=0; i<m; i++){
        a[i].id = i;
        scanf("%d %d", &(a[i].p), &(a[i].y));
    }
    qsort(a, m, sizeof(node), cmp1);
    int x = a[0].p, y = 1;
    for(int i=0; i<m; i++){
        if(a[i].p == x){
            a[i].y = y;
            y++;
        }else{
            y = 1;
            x = a[i].p;
            a[i].y = y;
        }
    }
    qsort(a, m, sizeof(node), cmp2);
    for(int i=0; i<m; i++){
        printf("%06d%06d\n", a[i].p, a[i].y);
    }

    return 0;
}