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: Time Limit Exceeded)

#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <ostream>
#include <iomanip>

using namespace std;

bool find(int x, vector<int> &tmp);

int main() {

    unsigned int N;
    unsigned int M;
    int maxPrefecNum = 0;
    vector<pair<int, int>> city;
    vector<pair<int, int>> result;
    vector<int> saveCityNum;

    cin>>N>>M;
    city.resize(M);
    result.resize(M);
    saveCityNum.resize(M);

    int a, b;
    for(int i=0; i<M; ++i)
    {
        cin>>a>>b;
        city[i].first =a-1;
        city[i].second = b;
        if(a>maxPrefecNum)
            maxPrefecNum = a-1;
        saveCityNum[i] = a-1;
    }

    for(int prefecNum=0; prefecNum<=maxPrefecNum; ++prefecNum)
    {
        if(find(prefecNum, saveCityNum))
            continue;

        map<int, int> eachPre;

        for(int i=0; i<M; ++i)
        {
            if(city[i].first == prefecNum)
                eachPre[city[i].second]=i;
        }

        for(auto i=eachPre.begin(); i!=eachPre.end(); ++i)
        {
                result[i->second].first = prefecNum+1;
                result[i->second].second = distance(eachPre.begin(), i)+1;
        }
    }

    for(int i=0; i<M; ++i)
    {
        cout<<setfill('0')<<setw(6)<<result[i].first;
        cout<<setfill('0')<<setw(6)<<result[i].second<<endl;
    }


    return 0;
}

bool find(int x, vector<int> &tmp)
{
    for (int i : tmp) {
        if(i ==x)
            return false;
    }

    return true;
}