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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

public class Main {
	public static void main(String[] args) {
		FastReader sc = new FastReader();
		PrintWriter out = new PrintWriter(System.out);
		int n = sc.nextInt();
		int m = sc.nextInt();

		Map<Integer, List<Long>> dic = new HashMap<>();
		List<Pair> toi = new ArrayList<>();
		for (int i = 0; i < m; i++) {
			int x = sc.nextInt();
			long y = sc.nextLong();
			toi.add(new Pair(x, y));
			List<Long> list = dic.getOrDefault(x, new ArrayList<>());
			list.add(y);
			dic.put(x, list);
		}

		Map<Integer, Long[]> sortDic = new HashMap<>();
		dic.entrySet().stream().forEach(e -> {
			Long[] tmp = e.getValue().toArray(new Long[e.getValue().size()]);
			Arrays.sort(tmp);
			sortDic.put(e.getKey(), tmp);
		});

		for (int i = 0; i < toi.size(); i++) {
			Pair mon = toi.get(i);
			String x = String.valueOf(mon.x);
			String paddingleft = x.format("%6s", x).replace(" ", "0");
			String index = String.valueOf(Arrays.binarySearch(sortDic.get(mon.x), mon.y) + 1);
			String paddingRight = index.format("%6s", index).replace(" ", "0");
			out.println(paddingleft + paddingRight);
		}

	}

	static class Pair {
		public int x;
		public long y;

		public Pair(int x, long y) {
			this.x = x;
			this.y = y;
		}
	}

	static class FastReader {
		BufferedReader br;
		StringTokenizer st;

		public FastReader() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
	}
}