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 <bits/stdc++.h>

using namespace std;

int main() {
    int N, M;
    vector <vector<int> > data(100000);
    int p[100000];
    int y[100000];

    cin >> N >> M;
    for (int i = 0; i < M; i++) {
        cin >> p[i] >> y[i];

        data[p[i]-1].push_back(y[i]);
    }

    for (int i = 0; i < N; i++) {
        sort(data[i].begin(), data[i].end());
    }

    for (int i = 0; i < M; i++) {
        const vector<int> &pref = data[p[i]-1];
        int pref_len = pref.size();

        for (int j = 0; j < pref_len; j++) {
            if (pref[j] == y[i]) {
                string p_str = to_string(p[i]);
                string x_str = to_string(j+1);
                string out_str ="";

                int p_len = p_str.size();
                int x_len = x_str.size();

                for (int k = 0; k < 6-p_len; k++) out_str += "0";
                out_str += p_str;
                for (int k = 0; k < 6-x_len; k++) out_str += "0";
                out_str += x_str;

                cout << out_str << endl;
                break;
            }
        }
    }

    return 0;
}