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>
using namespace std;
#define ll long long int
#define ld long double
#define LL_MAX LLONG_MAX
#define ULL_MAX ULLONG_MAX
#define ull unsigned long long
#define IOS ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define pb(x) push_back(x)
#define re() pop_back()
#define eb(x) emplace_back(x)
#define forn(i, n) for (int i = 0; i < int(n); ++i)
#define fore(i, l, r) for (int i = int(l); i < int(r); ++i)
#define all(a) a.begin(),a.end()
#define msort(a) sort(a.begin(),a.end())
#define pii pair<int,int>
#define sz(x) int(x.size())
#define mk make_pair
#define endl '\n'

const int N= 5e5+ 4;
vector<int> dat(N);
vector<int> last(N),c(N);

void update(int i,int val){
    while(i<N){
        dat[i]+=val;
        i+=i&-i;
    }
}

int sum(int i){
    int sum=0;
    while(i){
        sum+=dat[i];
        i-=i&-i;
    }
    return sum;
}

int rangesum(int l,int r) {
    return sum(r)-sum(l-1);
}


void sol()
{
    int n,q;
    cin>>n>>q;
    for (int i = 1; i < n+1; i++)
    {
        cin>>c[i];
    }

    int ans[n+1];
    vector<int> qi[n+1],qs[n+1];
    for (int i = 0; i <q; i++)
    {
        int x,y;
        cin>>x>>y;
        qi[y].eb(i);
        qs[y].eb(x);
    }
    
    for (int i = 1; i < n+1; i++)
    {
        if(last[c[i]]>0) {
            update(last[c[i]],-1);
        }
        update(i,1);
        last[c[i]]=i;
        for (int j = 0; j< sz(qs[i]); j++)
        {
            ans[qi[i][j]]=rangesum(qs[i][j],i);
        }
        
    }
    
    for (int i = 0; i < q; i++)
    {
        cout<<ans[i]<<endl;
    }
}

int main()
{
    IOS;
    ll t=1;// cin>>t;
    while (t--)
    {
        sol();
    }
}