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 REP(i,num) for(int i=0;i<(num);++i)
#define ALL(c) c.begin(),c.end()
#define PRINTALL(c) for(auto& x:c){cout<<x<<' ';}cout<<endl;
#define PAIRCOMP(c,comp) [](const pair<ll,ll>& lhs,const pair<ll,ll>& rhs){return lhs.c comp rhs.c;}

constexpr int atcoder_mod = 1e9+7;

using namespace std;
using ll = long long;

template<typename T=int>
T in(){T x; cin >> x; return (x);}

class Data{
public:
	int P,Y;
	int i,x;
};

int main(){
	//cin.tie(0);
	//ios::sync_with_stdio(false);

	int N=in(),M=in();
	vector<Data> D(M);
	REP(i,M){
		D[i].P=in();
		D[i].Y=in();
		D[i].i=i;
	}
	sort(ALL(D),[](Data& lhs,Data& rhs){return lhs.P==rhs.P ? lhs.Y<rhs.Y : lhs.P<rhs.P;});
	int number = 0,old_p = D[0].P;
	REP(i,M){
		if(D[i].P!=old_p){
			number = 1;
		}
		else number++;
		D[i].x = number;
		old_p = D[i].P;
	}
	sort(ALL(D),[](Data& lhs,Data& rhs){return lhs.i<rhs.i;});
	REP(i,M){
		printf("%06d%06d\n",D[i].P,D[i].x);
	}
	
	return 0;
}