Problem:
Score : 600 points

Problem Statement

We have N colored balls arranged in a row from left to right; the color of the i-th ball from the left is c_i.

You are given Q queries. The i-th query is as follows: how many different colors do the l_i-th through r_i-th balls from the left have?

Constraints

1\leq N,Q \leq 5 \times 10^5

1\leq c_i \leq N

1\leq l_i \leq r_i \leq N

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N Q
c_1 c_2 \cdots c_N
l_1 r_1
l_2 r_2
:
l_Q r_Q

Output

Print Q lines. The i-th line should contain the response to the i-th query.

Sample Input 1

4 3
1 2 1 3
1 3
2 4
3 3

Sample Output 1

2
3
1

The 1-st, 2-nd, and 3-rd balls from the left have the colors 1, 2, and 1 - two different colors.

The 2-st, 3-rd, and 4-th balls from the left have the colors 2, 1, and 3 - three different colors.

The 3-rd ball from the left has the color 1 - just one color.

Sample Input 2

10 10
2 5 6 5 2 1 7 9 7 2
5 5
2 4
6 7
2 2
7 8
7 9
1 8
6 9
8 10
6 8

Sample Output 2

1
2
2
1
2
2
6
3
3
3

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

using System.Linq;
using System.Text;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Security.Cryptography.X509Certificates;
using System.Diagnostics;
using System.Reflection.Metadata;
using System.Threading;

namespace AtCoder
{
    class Program
    {

        struct Point
        {
            public int left;
            public int right;

            public Point(int left, int right)
            {

                this.left = left;
                this.right = right;

            }

        }


        const int BiggestMod = 1000000007;

        public static void Main()
        {

            var args = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
            var n = args[0];
            var q = args[1];

            var core = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
            var conv = new int[n];
            var memo = new int[n][];
            var ans = new int[q];

            for (int i = 0; i < n; i++)
            {

                conv[i] = -1;
                for (int j = i - 1; 0 <= j; j--)
                    if (core[j] == core[i])
                    {
                        conv[i] = j;
                        break;
                    }

                memo[i] = new int[n - i];
                memo[i][0] = 1;

            }

            for (int i = 0; i < n; i++)
                for (int j = 1; j < n - i; j++)
                {

                    if (conv[i + j] < i)
                        memo[i][j] = memo[i][j - 1] + 1;
                    else
                        memo[i][j] = memo[i][j - 1];

                }

            for (int i = 0; i < q; i++)
            {

                var arg = Console.ReadLine().Split(' ').Select(x => int.Parse(x) - 1).ToArray();
                ans[i] = memo[arg[0]][arg[1] - arg[0]];

            }

            foreach (var answer in ans)
                Console.WriteLine(answer);

        }

    }

}