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++ (Clang 10.0.0) (judge verdict: Time Limit Exceeded)

#include <algorithm>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <ctime>
#include <deque>
#include <iostream>
#include <list>
#include <map>
#include <memory.h>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <unordered_map>
#include <unordered_set>
using namespace std;
typedef long double LD;
typedef long long LL;
typedef pair<LL, LL> pll;
typedef pair<int, int> pii;
typedef vector<int> vi;
#ifdef LOCAL
#define DEBUG(x) { cerr << "# " << #x << ": " << x << endl;}
#else
#define DEBUG(x)
#endif
mt19937_64 mt(time(0));
/*---------------------------------------------------------------------------------------------------
　　　　　　　　　　　 ∧＿∧
　　　　　 ∧＿∧ 　（´<_｀ ）　 Welcome to My Coding Space!
　　　　 （ ´_ゝ`）　/　 ⌒i
　　　　／　　　＼　 　  |　|
　　　 /　　 /￣￣￣￣/　　|
　 ＿_(__ﾆつ/　    ＿/ .| .|＿＿＿＿
　 　　　＼/＿＿＿＿/　（u　⊃
---------------------------------------------------------------------------------------------------*/
const int MAXN = 5e5 + 10;
const int block = 710;
int nums[MAXN];
int a[MAXN], b[MAXN], idx[MAXN], ret[MAXN];
map<int, int> batch[block];

void move(int x, int y, int xx, int yy, map<int, int>& table) {
  while (y < yy) {
    if (y % block == 0 && y+block <= yy) {
      for (const auto& item : batch[y/block]) {
        table[item.first] += item.second;
      }
      y += block;
    } else {
      table[nums[y]]++;
      y++;
    }
  }
  while (y > yy) {
    if (y % block == 0 && y-block >= yy) {
      for (const auto& item : batch[(y-1)/block]) {
        auto it = table.find(item.first);
        it->second -= item.second;
        if (it->second == 0) table.erase(it);
      }
      y -= block;
    } else {
      y--;
      auto it = table.find(nums[y]);
      it->second--;
      if (it->second == 0) table.erase(it);
    }
  }
  while (x < xx) {
    if (x % block == 0 && x+block <= xx) {
      for (const auto& item : batch[x/block]) {
        auto it = table.find(item.first);
        it->second -= item.second;
        if (it->second == 0) table.erase(it);
      }
      x += block;
    } else {
      auto it = table.find(nums[x]);
      it->second--;
      if (it->second == 0) table.erase(it);
      x++;
    }
  }
}


int main() {
  ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
  cout.precision(10); cout << fixed;
#ifdef LOCAL
  freopen("../test.txt", "r", stdin);
    // freopen("../output.txt", "w", stdout);
#endif
  int n, q; cin >> n >> q;
  for (int i = 0; i < n; i++) {
    cin >> nums[i];
    batch[i/block][nums[i]]++;
  }
  for (int i = 0; i < q; i++) {
    cin >> a[i] >> b[i];
    a[i]--;
    idx[i] = i;
  }
  sort(idx, idx+q, [](int i, int j) {
    return make_pair(a[i], b[i]) < make_pair(a[j], b[j]);
  });
  int x = 0, y = 0;
  map<int, int> table;
  for (int i = 0; i < q; i++) {
    move(x, y, a[idx[i]], b[idx[i]], table);
    ret[idx[i]] = table.size();
    x = a[idx[i]];
    y = b[idx[i]];
  }
  for (int i = 0; i < q; i++) {
    cout << ret[i] << '\n';
  }







/*---------------------------------------Coding Space End------------------------------------------*/
#ifdef LOCAL
  cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s." << endl;
#endif
  return 0;
}
/* author:  txingml */
/* picture is from hamayanhamayan(CF handle) */