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: Time Limit Exceeded)

#include<bits/stdc++.h>
using namespace std;
#define ll long int
#define sp <<" "<<

ll temp,temp1,temp2;
ll dp[500004];
int main()
{
    /*#ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif*/
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    ll n,q;
    cin>>n>>q;
    vector<ll> in(n+1);
    set<ll> temps;
    
    //memset(dp,-1,sizeof dp);

    for(int i=1;i<=n;i++)
    {
        cin>>in[i];
        temps.insert(in[i]);
        dp[i]=temps.size();
    }
    vector<vector<int>> qs;
    for(int i=0;i<q;i++)
    {
        cin>>temp1>>temp2;
        qs.push_back({temp1,temp2,i});
        //cout<<qs[0].first sp qs[0].second<<endl;
    }
    ll res[q];
    sort(qs.begin(),qs.end());
    ll para=0;

    for(int i=0;i<q;i++)
    {
        //cout<<qs[i][0] sp qs[i][1] sp qs[i][2]<<endl;
    }

    while(para<q&&qs[para][0]==1)
    {
        res[qs[para][2]]=dp[qs[para][1]];
        para++;
    }
    /*for(ll k=1;k<=10;k++)
        cout<<dp[k]<<" ";
    cout<<endl;*/
    for(ll i=2;i<=n;i++)
    {
        for(ll j=i;j<=n;j++)
        {
            //cout<<i sp j sp in[i-1] sp in[j]<<endl;
            if(in[j]==in[i-1])
            {
                break;
            }
            dp[j]=dp[j]-1;
        }
        /*for(ll k=1;k<=10;k++)
            cout<<dp[k]<<" ";
        cout<<endl;*/
        while(para<q&&qs[para][0]==i)
        {
            res[qs[para][2]]=dp[qs[para][1]];
            para++;
        }   
    }
    for(ll i=0;i<q;i++)
        cout<<res[i]<<endl;
    
    return 0;
}