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: Runtime Error)

using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
static class Program{
	const int mod=(int)1e9+7;
	const double eps=1e-11;
	static void Main(){
		Sc sc=new Sc();
		var s=sc.Ia;
		var a=sc.Ia2;
		var h=new int[s[0]+1];
		Fc2 fc=new Fc2();
		StringBuilder sb=new StringBuilder();
		for(int i = 1;i<=s[0];i++) {
			if(h[a[i]]!=0){fc.Ud(h[a[i]],i,1);}
			h[a[i]]=i;
		}
		for(int i = 0;i<s[1];i++) {
			var e=sc.Ia;
			sb.Append(e[1]-e[0]+1-fc.Get(e[0],e[1],e[0],e[1])+"\n");
		}
		Console.Write(sb);
	}
}
public class Fc2{
	public class Nd{
		public int h,m,x;
		public Nd l,r;
		public int[] dat1,dat2,dat3;
		public long[] dat4;
		public bool lf;
		public Nd(int x,Nd l,Nd r){this.x=x;this.l=l;this.r=r;lf=false;h=2;}
		public Nd(int x){this.x=x;lf=true;h=1;}
		public virtual void Ad(int y,long d){}
	}
	public class Nd1:Nd{
		public List<Tuple<int,long>> li=new List<Tuple<int,long>>();
		public Nd1(int x,int y,long d,Nd du):base(x){
			li.Add(Tuple.Create(y,d));
			l=r=du;
		}
		public override void Ad(int y,long d){li.Add(Tuple.Create(y,d));}
	}
	public Nd root,du;
	public int cnt=0;
	private bool bo=false;
	public Fc2(){
		du=new Nd(int.MinValue);du.h=0;
		root=du;
	}
	public void Ud(int x,int y,long d){
		if(!root.lf){
			Fu(root,x,y,d);
			if(Abs(root.l.h-root.r.h)>1){root=Rotate(root);}
		}
		else if(root!=du){
			if(root.x!=x){root=Flf(root,x,y,d);}
			else{root.Ad(y,d);}
		}
		else{root=new Nd1(x,y,d,du);}
		cnt++;
	}
	private void Fu(Nd t,int x,int y,long d){
		if(t.x>x){
			if(!t.l.lf){
				Fu(t.l,x,y,d);
				if(Abs(t.l.l.h-t.l.r.h)>1){t.l=Rotate(t.l);}
			}
			else if(t.l.x!=x){t.l=Flf(t.l,x,y,d);}
			else{t.l.Ad(y,d);}
		}
		else{
			if(!t.r.lf){
				Fu(t.r,x,y,d);
				if(Abs(t.r.l.h-t.r.r.h)>1){t.r=Rotate(t.r);}
			}
			else if(t.r.x!=x){t.r=Flf(t.r,x,y,d);}
			else{t.r.Ad(y,d);}
		}
		t.h=Max(t.l.h,t.r.h)+1;
	}
	private Nd Flf(Nd t,int x,int y,long d){
		var e=new Nd1(x,y,d,du);
		return t.x>x?new Nd(t.x,e,t):new Nd(x,t,e);
	}
	private Nd Rotate(Nd t){
		Nd nd=du;
		if(t.l.h>t.r.h){
			if(t.l.l.h>t.l.r.h){
				nd=t.l;t.l=t.l.r;nd.r=t;
				Ft(t);
			}
			else{
				nd=t.l.r;
				t.l.r=nd.l;nd.l=t.l;
				Ft(t.l);
				t.l=nd.r;nd.r=t;
				Ft(t);
			}
		}
		else{
			if(t.r.l.h>t.r.r.h){
				nd=t.r.l;
				t.r.l=nd.r;nd.r=t.r;
				Ft(t.r);
				t.r=nd.l;nd.l=t;
				Ft(t);
			}
			else{
				nd=t.r;t.r=t.r.l;nd.l=t;
				Ft(t);
			}
		}
		Ft(nd);
		return nd;
	}
	private void Ft(Nd t){
		if(!t.lf){t.h=Max(t.l.h,t.r.h)+1;}
	}
	public long Get(int x1,int x2,int y1,int y2){
		if(!bo){Dn();}
		int lb=-1,ub=root.dat1.Length,mid=0;
		while(ub-lb>1){
			mid=(ub+lb)>>1;
			if(root.dat1[mid]>y2){ub=mid;}
			else{lb=mid;}
		}
		int p=ub;
		lb=-1;ub=root.dat1.Length;
		while(ub-lb>1){
			mid=(ub+lb)>>1;
			if(root.dat1[mid]>=y1){ub=mid;}
			else{lb=mid;}
		}
		return Fdg(root,x1,x2,false,false,ub,p);
	}
	private long Fdg(Nd t,int a,int b,bool l,bool r,int la,int ra){
		if(t.lf){
			if(a<=t.x&&t.x<=b){return t.dat4[ra]-t.dat4[la];}
			else{return 0;}
		}
		if(l&&r){return t.dat4[ra]-t.dat4[la];}
		if(t.x>b){return Fdg(t.l,a,b,l,t.x<=b,t.dat2[la],t.dat2[ra]);}
		if(t.x<a){return Fdg(t.r,a,b,t.x>=a,r,t.dat3[la],t.dat3[ra]);}
		return Fdg(t.l,a,b,l,t.x<=b,t.dat2[la],t.dat2[ra])+Fdg(t.r,a,b,t.x>=a,r,t.dat3[la],t.dat3[ra]);
	}
	private void Dn(){
		Fu(root);
		bo=true;
	}
	private void Fu(Nd t){
		if(t.lf){
			var z=(Nd1)t;
			z.li.Sort((u,v)=>u.Item1-v.Item1);
			z.m=z.li.Count;
			z.dat1=new int[z.m];
			z.dat4=new long[z.m+1];
			for(int i = 0;i<z.m;i++) {
				z.dat1[i]=z.li[i].Item1;
				z.dat4[i+1]=z.dat4[i]+z.li[i].Item2;
			}
			return;
		}
		Fu(t.l);
		Fu(t.r);
		t.m=t.l.m+t.r.m;
		t.dat1=new int[t.m+1];
		t.dat2=new int[t.m+1];
		t.dat3=new int[t.m+1];
		t.dat4=new long[t.m+1];
		int j=0,k=0;
		long gl=0,gr=0;
		while(j<t.l.m&&k<t.r.m){
			if(t.l.dat1[j]<t.r.dat1[k]){
				t.dat1[j+k]=t.l.dat1[j];
				t.dat4[j+k+1]=t.l.dat4[j+1]+gr;
				gl=t.l.dat4[j+1];
				j++;
			}
			else{
				t.dat1[j+k]=t.r.dat1[k];
				t.dat4[j+k+1]=t.r.dat4[k+1]+gl;
				gr=t.r.dat4[k+1];
				k++;
			}
			t.dat2[j+k]=j;
			t.dat3[j+k]=k;
		}
		while(j<t.l.m){
			t.dat1[j+k]=t.l.dat1[j];
			t.dat2[j+k]=j;
			t.dat3[j+k]=k;
			t.dat4[j+k+1]=t.l.dat4[j+1]+gr;
			j++;
		}
		while(k<t.r.m){
			t.dat1[j+k]=t.r.dat1[k];
			t.dat2[j+k]=j;
			t.dat3[j+k]=k;
			t.dat4[j+k+1]=t.r.dat4[k+1]+gl;
			k++;
		}
		t.dat1[j+k]=int.MaxValue;
		t.dat2[j+k]=j;
		t.dat3[j+k]=k;
	}
}
public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),int.Parse);}
	public int[] Ia3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),long.Parse);}
	public long[] La3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
}