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: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;
#define int ll
#define ll long long

#define I32_MAX 2147483647
#define I64_MAX 9223372036854775807LL
#define I64_MAX2 1223372036854775807LL
#define INF I64_MAX2
#define MOD 1000000007
// #define MOD 998244353 
#define MEM_SIZE 500010
#define DEBUG_OUT true
#define ALL(x) (x).begin(), (x).end()


template<typename T> void DEBUG(T e){if(DEBUG_OUT == false)return; std::cout << e <<" ";}
template<typename T> void DEBUG(const std::vector<T>& v){if(DEBUG_OUT == false)return;for(const auto& e : v){std::cout<< e << " "; } std::cout << std::endl;}
template<typename T> void DEBUG(const std::vector<std::vector<T> >& vv){if(DEBUG_OUT == false)return;for(const auto& v : vv){ DEBUG(v); } }
template<class T,class... Ts> void DEBUG(T d, Ts... e){if(DEBUG_OUT == false)return;DEBUG(d);DEBUG(e...);}
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; abort();}}
template< typename T1, typename T2 > inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template< typename T1, typename T2 > inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

int dataa[MEM_SIZE];
int vec[MEM_SIZE];
int sum;
struct Mo
{
  vector< int > left, right, order;
  vector< bool > v;
  int width;
  int nl, nr, ptr;

  Mo(int n) : width((int)sqrt(n)), nl(0), nr(0), ptr(0), v(n) {}

  void insert(int l, int r) /* [l, r) */
  {
    left.push_back(l);
    right.push_back(r);
  }

  /* ソート */
  void build()
  {
    order.resize(left.size());
    iota(begin(order), end(order), 0);
    sort(begin(order), end(order), [&](int a, int b)
    {
      if(left[a] / width != left[b] / width) return left[a] < left[b];
      return right[a] < right[b];
    });
  }

  /* クエリを 1 つぶんすすめて, クエリのidを返す */
  int process()
  {
    if(ptr == order.size()) return (-1);
    const auto id = order[ptr];
    while(nl > left[id]) distribute(--nl);
    while(nr < right[id]) distribute(nr++);
    while(nl < left[id]) distribute(nl++);
    while(nr > right[id]) distribute(--nr);
    return (order[ptr++]);
  }

  inline void distribute(int idx)
  {
    v[idx].flip();
    
    if(v[idx]) add(idx);
    else del(idx);
  }

  void add(int idx);

  void del(int idx);
};

void Mo::add(int idx)
{
  if(vec[dataa[idx]] ++ == 0) ++ sum;
}


void Mo::del(int idx)
{
  if(-- vec[dataa[idx]] == 0) -- sum;
}


void solve(void)
{
  int n,q;
  scanf("%lld %lld",&n,&q);
  vector<int> data(n,0);
  for (int i = 0; i < n; i++)
  {
    int x;
    scanf("%lld",&x);
    data[i] = x;
  }
  Mo mo(n);
  for (int i = 0; i < q; i++)
  {
    int a,b;
    // cin>>a>>b;
    scanf("%lld %lld",&a,&b);
    mo.insert(--a,b);
  }
  mo.build();
  vector<int> ans(q,0);
  for (int i = 0; i < q; i++)
  {
    int idx = mo.process();
    ans[idx] = sum;
  }
  for (int i = 0; i < q; i++)
  {
    printf("%d\n",ans[i]);
  }
  
  
  

  return;
}

int32_t main(int32_t argc, const char *argv[])
{
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  std::cout << std::fixed;
  std::cout << std::setprecision(11);
  solve();

  return 0;
}