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 <stdio.h>
#include <iostream>
#include <map>
#include <vector>
#include <string>
#include <algorithm>

using namespace std;
using ll = long long;
using ld = long double;

struct ID{
    ll number;
    ll year;
    string S;
};

int main() {

    ll N, M;
    map<ll,vector<ID>> PY;
    cin >> N >> M;
    for (int i = 0; i < M; ++i) {
        ll p, y;
        cin >> p >> y;
        if(PY.count(p) == 0){
            vector<ID> v;
            ID id;
            id.number = i;
            id.year =y;
            v.push_back(id);
            PY[p] = v;
        } else{
            auto py = PY[p];
            ID id;
            id.number = i;
            id.year =y;
            py.push_back(id);
            PY[p] = py;
        }
    }

    for(auto itr=PY.begin(); itr != PY.end(); ++itr){
        auto a = itr->first;
        auto v = itr->second;
        sort(v.begin(),v.end(),
             [](const ID& a, const ID& b){return a.year < b.year;});
        PY[a] = v;
    }


    for(auto itr=PY.begin(); itr != PY.end(); ++itr){
        auto a = itr->first;
        auto v = itr->second;
        for (int i = 0; i < v.size(); ++i) {

            auto id = v[i];
            char c[20];
            sprintf(c, "%06d", a);
            string s = c;
            char c2[20];
            sprintf(c2, "%06d", i+1);
            string s2 = c2;
            id.S = s + s2;
            v[i] = id;
        }
        PY[a] = v;
    }

    map<ll, string> R;
    for(auto itr=PY.begin(); itr != PY.end(); ++itr){
        auto a = itr->first;
        auto v = itr->second;
        for (int i = 0; i < v.size(); ++i) {
            auto id = v[i];
            string s = id.S;
            R[id.number] = s;
        }
    }

    for (int i = 0; i < M; ++i) {
        cout << R[i] << endl;
    }


    return 0;
}