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 JavaScript (Node.js 12.16.1) (judge verdict: Time Limit Exceeded)

process.stdin.resume();
process.stdin.setEncoding('utf-8');
 
let inputString = '';
let currentLine = 0;
 
process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});
 
process.stdin.on('end', _ => {
    inputString = inputString.split(/\n/);
    main();    
});
 
function readLine() {
    return inputString[currentLine++];
}

function main() {
  const [n, q] = readLine().split(/\s/).map(Number)
  const cs = readLine().split(/\s/).map(Number)
  const qs = []
  const qMap = []
  for (let i = 0; i < q; i++) {
    qs.push(readLine())
    const [l, r] = qs[i].split(/\s/).map(Number)
    if (!qMap[r]) {
      qMap[r] = []
    }
    qMap[r].push(l)
  }
  const lastIndices = Array(n + 1)
  const tree = Array(n + 1)
  const results = {}
  for (let r = 1; r <= n; r++) {
    const color = cs[r - 1]
    const last = lastIndices[color]
    lastIndices[color] = r
    if (last) {
      add(tree, n, last, -1)
    }
    add(tree, n, r, 1)
    if (qMap[r]) {
      const sumR = sum(tree, n, r)
      for (let i = 0; i < qMap[r].length; i++) {
        const l = qMap[r][i]
	    results[l + ' ' + r] = sumR - sum(tree, n, l - 1)
      }
    }
  }
  console.log(qs.map(q => results[q]).join('\n'))
}
function add(tree, n, i, delta) {
  for (; i <= n; i = i | (i + 1)) {
    tree[i] = (tree[i] || 0) + delta
  }
}
function sum(tree, n, r) {
  let result = 0;
  for (; r > 0; r = (r & (r + 1)) - 1) {
    result += (tree[r] || 0)
  }
  return result;
}