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: Accepted)

#include <iostream>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
vector<pair<int, int>>v[100010];//年度、市名
pair<int, int>P[100010];//県名、順番
int main(){
	int n, m;
	int p[100010], y[100010];
	cin >> n >> m;
	rep(i, m) {
		cin >> p[i] >> y[i];
		v[p[i]].push_back({ y[i],i });
	}
	rep(i, n + 1) {
		sort(v[i].begin(), v[i].end());
		rep(j, v[i].size()) {
			P[v[i][j].second] = { i,j + 1 };
		}
	}
	rep(i, m) {
		if (P[i].first < 10)cout << "00000" << P[i].first;
		else if (P[i].first < 100)cout << "0000" << P[i].first;
		else if (P[i].first < 1000)cout << "000" << P[i].first;
		else if (P[i].first < 10000)cout << "00" << P[i].first;
		else if (P[i].first < 100000)cout << "0" << P[i].first;
		else cout << P[i].first;
		if (P[i].second < 10)cout << "00000" << P[i].second;
		else if (P[i].second < 100)cout << "0000" << P[i].second;
		else if (P[i].second < 1000)cout << "000" << P[i].second;
		else if (P[i].second < 10000)cout << "00" << P[i].second;
		else if (P[i].second < 100000)cout << "0" << P[i].second;
		else cout << P[i].second;
		cout << endl;
	}
	
	getchar();getchar();
	return 0;
}