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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

struct MyStruct
{
	int no,year,pre,id_b;
	long long num;
};

bool cmp_no(const MyStruct &a, const MyStruct &b) {
	return a.no < b.no;
}

bool cmp_num(const MyStruct &a, const MyStruct &b) {
	return a.num < b.num;
}

int main() {
	vector<MyStruct> v;
	int N, M;

	cin >> N >> M;

	for (int i = 0; i < M; i++)
	{
		MyStruct tmp;
		cin >> tmp.pre >> tmp.year;
		tmp.no = i + 1;
		tmp.num = tmp.pre * 100000 + tmp.year;
		v.push_back(tmp);
	}

	sort(v.begin(), v.end(), cmp_num);

	for (int i = 0; i < M; i++)
	{
		if (i == 0) {
			v[i].id_b = 1;
		}
		else {
			if (v[i - 1].pre == v[i].pre) {
				v[i].id_b = v[i - 1].id_b + 1;
			}
			else {
				v[i].id_b = 1;
			}
		}
	}

	sort(v.begin(), v.end(), cmp_no);
	for (int i = 0; i < M; i++)
	{
		printf("%06d%06d\n", v[i].pre, v[i].id_b);
	}

	return 0;
}