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# (Mono-csc 3.5.0) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Numerics;
using static System.Console;
using static System.Math;
using static System.Array;

class Program
{
	public static void Main()
	{
		var n = ReadLine().Split().Select(ushort.Parse).ToArray();
		var a = ReadLine().Split().Select(ushort.Parse).ToArray();
		var m = new Dictionary<Tuple<ushort, ushort>, ushort>();
		for(ushort i = 0; i < n[1]; i++)
		{
			var q = ReadLine().Split().Select(x => ushort.Parse(x) - 1).ToArray();
			if(!m.ContainsKey(new Tuple<ushort, ushort>((ushort)q[0], (ushort)q[1])))
			{
				var set = new HashSet<ushort>();
				for(ushort k = (ushort)q[0]; k <= q[1]; k++)
				{
					set.Add(a[k]);
					if(!m.ContainsKey(new Tuple<ushort, ushort>((ushort)q[0], k)))
						m.Add(new Tuple<ushort, ushort>((ushort)q[0], k), (ushort)set.Count);
				}
			}
			WriteLine(m[new Tuple<ushort, ushort>((ushort)q[0], (ushort)q[1])]);
		}
	}
}