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<string>
#include<vector>
#include<stack>
#include<set>
#include<map>
#include<utility>
#include<numeric>
#include<algorithm>
#include<cmath>
#include<climits>
using namespace std;

#define MOD 1000000007;

int main(){
	int n, m;
	cin >> n >> m;
	vector<pair<int, int> > c(m);
	for(int i=0; i<m; i++)
		cin >> c[i].first >> c[i].second;
	vector<int> num(m);
	iota(num.begin(), num.end(), 0);
	sort(num.begin(), num.end(), [=](int x, int y){
		return c[x]<c[y];
	});
	vector<string> id(m);
	int p=1, y=1;
	for(int i=0; i<m; i++){
		if(c[num[i]].first!=p){
			p=c[num[i]].first;
			y=1;
		}
		id[num[i]].push_back('0'+p/100000);
		id[num[i]].push_back('0'+p/10000%10);
		id[num[i]].push_back('0'+p/1000%10);
		id[num[i]].push_back('0'+p/100%10);
		id[num[i]].push_back('0'+p/10%10);
		id[num[i]].push_back('0'+p%10);
		id[num[i]].push_back('0'+y/100000);
		id[num[i]].push_back('0'+y/10000%10);
		id[num[i]].push_back('0'+y/1000%10);
		id[num[i]].push_back('0'+y/100%10);
		id[num[i]].push_back('0'+y/10%10);
		id[num[i]].push_back('0'+y%10);
		y++;
	}
	for(auto e: id) cout << e << endl;
	return 0;
}