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: Runtime Error)

#include <stdio.h>
#include <stdlib.h>
int cmp(const void *a, const void *b) {
    return *(int*)a - *(int*)b;
}

int main() {
    int N, M, pos;
    if (scanf("%d %d%*c", &N, &M) == -1) return -1;
    int cnt[N];
    long int P[M], Y[M], PY[N][M];
    for (int i = 0; i < N; i++) cnt[i] = 0;
    for (int i = 0; i < M; i++) {
        if (scanf("%ld %ld%*c", &P[i], &Y[i]) == -1) return -1;
        PY[P[i]-1][cnt[P[i]-1]++] = Y[i];
    }
    for (int i = 0; i < N; i++) qsort(PY[i], cnt[i], sizeof(long int), cmp);
    for (int i = 0; i < M; i++) {
        for (int j = 0; j < cnt[P[i]-1]; j++) if (Y[i] == PY[P[i]-1][j]) {
            pos = j;
            break;
        }
        printf("%06ld%06d\n", P[i], pos+1);
    }
    
    return 0;
}