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 Java (OpenJDK 11.0.6) (judge verdict: Time Limit Exceeded)

import java.util.*;

public class Main {
    int[] BIT;

    void add(int i, int x){
        if (i == 0) return;
        for (int k = i; k < BIT.length ; k += (k & -k)) {
            BIT[k] += x;
        }
    }

    int sum(int i){
        if(i == 0) return 0;

        int s = 0;
        for (int k=i; k > 0; k -= (k & -k)){
            s += BIT[k];
        }
        return s;
    }

    class Query {
        int index, left, right;
        int ans = 0;

        public Query(int index, int left, int right) {
            this.index = index;
            this.left  = left;
            this.right = right;
        }
    }

    public Main() {
        Scanner scanner = new Scanner(System.in);
        int N = scanner.nextInt();
        int Q = scanner.nextInt();

        int[] C = new int[N+1];
        for (int i = 1; i <= N; i++) {
            C[i] = Integer.valueOf(scanner.next());
        }

        ArrayList<Query> QL = new ArrayList<>();
        for (int i = 0; i < Q; i++) {
            QL.add(new Query(i, Integer.valueOf(scanner.next()), Integer.valueOf(scanner.next())));
        }

        //right昇順でソート
        Collections.sort(QL, new Comparator<Query>() {
            @Override
            public int compare(Query o1, Query o2) {
                return o1.right - o2.right;
            }
        });

        BIT = new int[N+1];
        int[] CP = new int[N+1]; //添え字色の最も右に存在する球の場所
        Arrays.fill(CP,-1);
        int index = 1;
        for (Query q : QL){
            while(index <= q.right){
                if (CP[C[index]] != -1) add(CP[C[index]], -1);
                add(index, 1);
                CP[C[index]] = index;
                index++;
            }
            q.ans = sum(q.right) - sum(q.left-1);
        }

        //index昇順でソート
        Collections.sort(QL, new Comparator<Query>() {
            @Override
            public int compare(Query o1, Query o2) {
                return o1.index - o2.index;
            }
        });

        for (Query q: QL){
            System.out.println(q.ans);
        }

    }

    public static void main(String[] args) {
        new Main();
    }
}