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 <iomanip>
#include <vector>
#include <array>
#include <algorithm>
using namespace std;

int main() {
	int N,M;
	cin >> N >> M;
	vector<array<int,2>> DAT;
	vector<int> C;
	vector<vector<int>> V;
	for (int i=0; i<M; i++) {
		int pi,yi;
		cin >> pi >> yi;
		auto itr = find(C.begin(), C.end(), pi);
    if( itr != C.end() ) {
			V[itr - C.begin()].push_back(yi);
    } else {
			C.push_back(pi);
			vector<int> vtmp(1,yi);
			V.push_back(vtmp);
		}
		array<int,2> dtmp{pi,yi};
		DAT.push_back(dtmp);
	}
	for (int i=0; i<V.size(); i++) {
		sort(V[i].begin(), V[i].end());
	}
	for (int i=0; i<M; i++) {
		int num;
		auto itr = find(C.begin(), C.end(), DAT[i][0]);
    if( itr != C.end() ) {
			int k =	itr - C.begin();
			auto jtr = find(V[k].begin(), V[k].end(), DAT[i][1]);
			num = jtr - V[k].begin()+1;
    } 
		cout << setfill('0') << right << setw(6) << DAT[i][0] << setfill('0') << right << setw(6) << num << endl;
	}
	return 0;
}