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: Runtime Error)

#include <bits/stdc++.h>

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define rep(i,n) FOR(i,0,n)
#define RFOR(i,a,b) for(int i=(a)-1;i>=(b);i--)
#define rrep(i,n) RFOR(i,n,0)

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;

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

	int n, m;
	cin >> n >> m;

	vector<pii> v[n+1];

	for(int i = 0; i < m; i++){
		int p, y;
		cin >> p >> y;

		v[p].push_back((pii){y, i});
	}

	pii w[n];
	for(int i = 1; i <= n; i++){
		if(v[i].size() > 0){
			sort(v[i].begin(), v[i].end());
			for(int j = 0; j < v[i].size(); j++){
				pii x = v[i][j];
				w[x.second] = (pii){i, j+1};
			}
		}
	}

	for(int i = 0; i < m; i++){
		pii x = w[i];
		cout << setfill('0') << setw(6) << x.first;
		cout << setfill('0') << setw(6) << x.second << endl;
	}

	return 0;
}