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 <iostream>

using namespace std;

int main(void){
  int N, Q;
  cin >> N; cin >> Q;
  int *color_arr = new int[N];
  for (int i = 0; i < N; i++) {
    int tmp;
    cin >> tmp;
    color_arr[i] = tmp - 1;
  }

  int **accum = new int*[N+1];
  	// 配列の各要素でintの配列を動的生成
  	for( int i=0; i<N+1; i++ ){
  		accum[i] = new int[N];
  	}

  for (int i = 0; i < N+1; i++)
  for (int j = 0; j < N; j++)
    accum[i][j] = 0;


  //1st ith: accum for 1..i
  //2nd jth: a count of the certain color for i..i

  for (int i = 0; i < N; i++){
      accum[i][color_arr[i]]++;
      for (int color = 0; color < N; color++){
        accum[i+1][color] += accum[i][color];
      }
  }

  for (int i = 0; i < Q; i++){
    int l, r;
    cin >> l; cin >> r;
    l--;
    r--;

    int count = 0;
    for (int color = 0; color < N; color++){
        int rCount = accum[r][color];
        int lCount = l-1 >= 0 ? accum[l-1][color] : 0;
        if (rCount > lCount) count++;
    }
    cout << count << endl;
  }

}