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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;

public class Main {

  public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] strs = br.readLine().split("\\s+");
    int n = Integer.parseInt(strs[0]);
    int q = Integer.parseInt(strs[1]);
    Map<Integer, Map<Integer, Integer>> map = new HashMap<>();
    Map<Integer, Integer> curr = new HashMap<>();
    strs = br.readLine().split("\\s+");
    for (int i = 0; i < n; i++) {
      int num = Integer.parseInt(strs[i]);
      curr.put(num, curr.getOrDefault(num, 0) + 1);
      map.put(i, new HashMap<>(curr));
    }
    for (int i = 0; i < q; i++) {
      strs = br.readLine().split("\\s+");
      int left = Integer.parseInt(strs[0]) - 1;
      int right = Integer.parseInt(strs[1]) - 1;
      Map<Integer, Integer> rightMap = map.get(right);
      if (left == 0) {
        System.out.println(rightMap.size());
      }
      else {
        Map<Integer, Integer> leftMap = map.get(left - 1);
        int count = rightMap.size();
        for (Integer key : leftMap.keySet()) {
          int val = rightMap.get(key) - leftMap.get(key);
          if (val == 0) {
            count--;
          }
        }
        System.out.println(count);
      }
    }
  }
}