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# (.NET Core 3.1.201) (judge verdict: Time Limit Exceeded)

using System;
using System.Linq;

namespace C
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] In = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
            int n = In[0];
            int m = In[1];
            var PY = new Pair[m];
            for(int i = 0; i < m; i++)
            {
                int[] In2 = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
                int p = In2[0];
                int y = In2[1];
                PY[i] = new Pair(p, y);
            }
            var z = PY.OrderBy(_ => _.x).ThenBy(_ => _.y).ToArray();
            for(int i=0; i < m; i++)
            {
                string text = "";
                text = PY[i].x.ToString("000000");
                var zz = z.Where(_ => _.x == PY[i].x).ToArray();
                for(int j = 0; j < zz.Length; j++)
                {
                    if (PY[i].y == zz[j].y)
                    {
                        j++;
                        text += j.ToString("000000");
                        break;
                    }
                }
                Console.WriteLine(text);
            }
        }
    }
    public struct Pair
    {
        public int x, y;
        public Pair(int x, int y)
        {
            this.x = x;
            this.y = y;
        }
    }
}