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# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;
using System.Linq;
using System.Collections.Generic;

namespace ConsoleApp1 {
    public class Class1 {
        static void Main(string[] args) {
            var X = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            var N = X[0];
            var M = X[1];

            var G = new List<long>[N];
            for (var i = 0; i < N; i++) G[i] = new List<long>();

            var P = new long[M];
            var Y = new long[M];

            for (var i = 0; i < M; i++) {
                var A = Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
                G[A[0] - 1].Add(A[1]);
                P[i] = A[0];
                Y[i] = A[1];
            }

            for (var i = 0; i < N; i++) G[i].Sort();

            for (var i = 0; i < M; i++) {
                Y[i] = G[P[i] - 1].FindIndex(x => x == Y[i]) + 1;
            }

            for (var i = 0; i < M; i++) {
                Console.WriteLine("{0}{1}", P[i].ToString("D6"), Y[i].ToString("D6"));
            }
        }
    }
}