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 <bits/stdc++.h>
#define ll long long
using namespace std;
 
int main() {

	ll n,m;cin>>n>>m;
	vector<pair<ll,ll>> vc;
	ll a,b;
	ll d[m+1],f[m+1];
	map<ll,ll> mp;
	for(int i=1;i<=m;i++){
	cin>>d[i]>>f[i]	;
	vc.push_back({d[i],f[i]});}
	
	sort(vc.begin(),vc.end());
	int count=1;
	mp[vc[0].second]+=count;
	
	for(int i=1;i<vc.size();i++)
	{
		if(vc[i].first==vc[i-1].first){
		count++;
		mp[vc[i].second]+=count;}
		else{
		count=1;
		mp[vc[i].second]+=count;}
	}
	
	for(int i=1;i<=m;i++)
	{
		string res=to_string(d[i]);
		ll zero=6-res.length();
		for(int j=0;j<zero;j++)
		cout<<"0";
		cout<<res;
		
	res=to_string(mp[f[i]]);
     zero=6-res.length();
		for(int j=0;j<zero;j++)
		cout<<"0";
		cout<<res;
		
		cout<<"\n";
	}
	
	
}