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++ (GCC 9.2.1) (judge verdict: Runtime Error)

//#include<bits/stdc++.h>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<stdlib.h>
#include<queue>
#include<map>
#include<vector>
#include<cmath>
#include<fstream>
#include <set>
//freopen(".in","r",stdin);
//freopen(".out","w",stdout);
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
const int  MAXN =5e5+10;
const int mod = 1e9 + 7;
const long long INF = 0x7f7f7f7f7f7f7f7f;
const int inf= 0x3f3f3f3f;
#define eps 1e-8
#define PI 3.1415926535898
#define lowbit(x) (x&(-x))
using namespace std ;
//getline(cin,s);
//set<ll>::iterator it;
//map<int,int>::iterator it;
typedef long long ll;
int n,q;
int c[MAXN],ans[MAXN],rt,pos[MAXN],sum;
map<int,int>mp;
struct node{
	int l,r,index;
}need[MAXN];
bool cmp(node x,node y)
{
	if(pos[x.l]==pos[y.l]) return x.r<y.r;
	else return x.l<y.r;
}
void add(int x)
{
	mp[c[x]]++;
	if(mp[c[x]]==1) sum++;
}
void del(int x)
{
	mp[c[x]]--;
	if(mp[c[x]]==0) sum--;
}
int main()
{
	scanf("%d %d",&n,&q);
	rt=(int)sqrt(n);
	for(int i=1;i<=n;i++)
	{
	    scanf("%d",&c[i]);
	    pos[i]=i/rt; 
	} 
	for(int i=1;i<=q;i++)
	{
		scanf("%d %d",&need[i].l,&need[i].r);
		need[i].index=i;
	}
	sort(need+1,need+1+q,cmp);
	int l=1,r=0;
	for(int i=1;i<=q;i++)
	{
		while(l<need[i].l)
		{
			del(l);
			l++;
		}
		while(l>need[i].l)
		{
			l--;
			add(l);
		}
		while(r<need[i].r)
		{
			r++;
			add(r);
		}
		while(r>need[i].r)
		{
			del(r);
			r--;
		}
		ans[need[i].index]=sum;
	}
	for(int i=1;i<=q;i++) printf("%d\n",ans[i]);
	return 0;
}