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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <algorithm>
#include <vector>
#include <complex>
#include <set>
#include <map>
#include <string>

using namespace std;

bool sortVec(pair<int, int> p1, pair<int, int> p2)
{
    return p1.second < p2.second;
}

int main() {
    int n, m;
    cin >> n; cin >> m;

    int p[m];
    vector<pair<int, int>> vec[n + 1];

    for(int i=0; i<m; i++)
    {
        int y;
        cin >> p[i]; cin >> y;
        vec[p[i]].emplace_back(make_pair(i, y));
    }

    for(int i=0; i<=n; i++) sort(vec[i].begin(), vec[i].end(), sortVec);

    int order[m];
    for(int i=0; i<=n; i++)
    {
        for(int j=0; j<vec[i].size(); j++)
        {
            order[vec[i][j].first] = j + 1;
        }
    }

    for(int i=0; i<m; i++)
    {
        printf("%06d%06d\n", p[i], order[i]);
    }

    return 0;
}