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<string>
#include<vector>
#include<algorithm>
#include<iomanip>
#include<ios>

using ll = unsigned long long;
using namespace std;

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

    vector<ll> p(m), y(m);
    for (int i = 0; i < m; ++i){
        cin >> p[i] >> y[i];
    }

    vector<vector<ll>> py(n);
    for(int i = 0; i < m; ++i) {
        // piを0-indexにして保存
        py[p[i]-1].push_back(y[i]);
    }

    // すべての県の所在地を設立年でソート
    for( int i = 0; i < n; ++i) {
        if (py[i].size() > 1) {
            std::sort(py[i].begin(), py[i].end());
        }
    }
    
    for(int i = 0; i < m; ++i) {
        // 6桁表示 prefecture id
        cout << setfill('0') << right << setw(6) << p[i];
        // city id
        cout << setfill('0') << right << setw(6) <<find(py[p[i]-1].begin(), py[p[i]-1].end(), y[i]) -  py[p[i]-1].begin() + 1<< endl;
    }

    return 0;
}