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: Time Limit Exceeded)

//Konrad Paluszek,University of Warsaw(former XIV LO Staszic)
//#STAY AT HOME
#ifndef LOCAL
#pragma GCC optimize("O3")
#endif
#define TIME (chrono::steady_clock::now().time_since_epoch().count())
#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#define xfm(a,b)a##b
#define xwb(a,b)xfm(a,b)
#define _ xwb(nvj,__LINE__)
#define __ xwb(kjy,__LINE__)
#define ___ xwb(cjm,__LINE__)
#define REP(i,n)for(urs(n)i=0;i<(n);++i)
#define UNTIL(t)while(clock()<(t)*CLOCKS_PER_SEC)
#define PER(r...)for(bool _=1;_||next_permutation(r);_=false)
#define ALL(r)(r).begin(),(r).end()
#define RALL(r)(r).rbegin(),(r).rend()
#define FS(r)r.first,r.second
#define SF(r)r.second,r.first
#define M0(r) memset(r, 0, sizeof(r))
#define sim template<class c
#define ros return o
#define rans return ans
#define forbits(i,m)if(m)for(urs(m)i=ctz(m),i##nvj=m;i##nvj;i##nvj^=((urs(m))1<<i),i=ctz(i##nvj))
#define fordbits(i,m)if(m)for(urs(m)i=8*sizeof(m)-clz(m)-1,i##nxd=m;i##nxd;i##nxd^=((urs(m))1<<i),i=8*sizeof(m)-clz(i##nxd)-1)
#define ksets(t, m, k, n) for (t m = (((t)1 << (k)) - 1); m < ((t)1 << (n)); m = nux(m))
#define urs(r...)typename decay<decltype(r)>::type
#define hur(f,g,r)sim>int f(c a){if(sizeof(c)==16)return r;if(sizeof(c)==8)return g##ll(a);return g(a);}
#define pwq(t,i) int clz(t x){return clz<int>(x)-i;}
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wconversion"
using namespace __gnu_pbds;using namespace std;using ll=long long;using ld=long double;using ull=unsigned long long;using vi=vector<int>;using vll=vector<ll>;using pii=pair<int,int>;using pll=pair<ll,ll>;using vpii=vector<pii>;using spii=set<pii>;using mii=map<int,int>;using unt=unsigned int;sim>using min_queue=priority_queue<c,vector<c>,greater<c>>;sim,class b,class cmp=less<c> >using ordered_map=tree<c,b,cmp,rb_tree_tag,tree_order_statistics_node_update>;sim, class cmp=less<c>>using ordered_set = ordered_map<c,null_type,cmp>;hur(popc,__builtin_popcount,popc<ull>(a)+popc<ull>(a>>64))hur(ctz,__builtin_ctz,(ull)a?ctz<ull>(a):64+ctz<ull>(a>>64))hur(clz,__builtin_clz,a>>64?clz<ull>(a>>64):64+clz<ull>(a))pwq(short,16)pwq(uint16_t,16)pwq(char,24)pwq(int8_t,24)pwq(uint8_t,24)sim,class N>bool mini(c&o,const N&h){if(o>h)ros=h,1;return 0;}sim,class N>bool maxi(c&o,const N&h){if(o<h)ros=h,1;return 0;}sim,class n>using gyv=c;
#if defined(LOCAL) // || defined(LOCAL2)
#include </home/kjp/headers/debuglib.hpp>
#else
#define loc(...)
#define onl(r...)r
#define debug(...)
#define print_stack(...)
#define mark_stack(...)
#define set_pre(...)
#define reg_it(...)
#define def_op(...) struct _{};
#if !defined(LOCAL) && !defined(LOCAL2)
#define exit my_exit
void my_exit(int x) {fflush(stdout);_Exit(x);}
#endif
#endif
#define next nexT
#define prev preV
#define tree trEE
#define left lefT
#define right righT
#define div diV
#define y1 y_1
#define pow do not use cmath pow unless you know what you are doing
ull mix(ull o){o+=0x9e3779b97f4a7c15;o=(o^(o>>30))*0xbf58476d1ce4e5b9;o=(o^(o>>27))*0x94d049bb133111eb;ros^(o>>31);}ull SALT=0x7a14a4b0881ebf9,tqu=0x7a14a4b0881ebf9;ull my_rand(){return tqu=mix(tqu);}void my_srand(ull x){SALT=tqu=x;}const int inf = 1023400000;const ll llinf=1234567890000000000ll;ll fix(ll o, ll m){o%=m;if(o<0)o+=m;ros;}
#define rand my_rand
#define srand my_srand
#define random_shuffle(r...)random_shuffle(r,[](int _){return my_rand()%_;})
sim>inline c nux(c m){if(!m)return numeric_limits<c>::max();c A=m&-m;c B=~((A-1)^m);c C=B&-B;c D=(C>>(1+ctz(A)))-1;return C|(m&~(C-1))|D;}__attribute__((no_sanitize_undefined))ll mul(ll a,ll b,ll m){ll q=(ll)(a*(ld)b/m);ll o=a*b-q*m;o%=m;if(o<0)o+=m;ros;}sim>void unq(c&x){x.resize(unique(ALL(x))-x.begin());}
#pragma GCC diagnostic pop
#if ((ULONG_MAX) != (UINT_MAX))
namespace std {template <> struct is_signed<__int128> : public true_type {};}
#endif
sim, class d> typename common_type<c,d>::type floor_div(c a, d b) {static_assert(is_signed<c>::value==is_signed<d>::value,"using floor_div with different signedness");if (b < 0) b = -b, a = -a;return a / b - (a % b < 0);}
sim, class d> typename common_type<c,d>::type ceil_div(c a, d b) {static_assert(is_signed<c>::value==is_signed<d>::value,"using ceil_div with different signedness");if (b < 0) b = -b, a = -a;return a / b + (a % b > 0);}
sim> struct REV {using value_type=typename c::value_type;c &x;using it=typename c::reverse_iterator;it begin(){return x.rbegin();}it end(){return x.rend();}};
sim> struct CREV {using value_type=typename c::value_type;const c&x;using it=typename c::const_reverse_iterator;it begin(){return x.rbegin();}it end(){return x.rend();}};
sim> REV<c> reversed(c&x) {return REV<c>{x};}sim> CREV<c> reversed(const c&x) {return CREV<c>{x};}
#define done(r...) exit(0 * printf(r))
#if defined(LOCAL) || defined(LOCAL2)
void __tmi() {cerr << setprecision(6) << fixed << "total time: " << clock() / (ld)CLOCKS_PER_SEC << "s" << endl;}int _ = (atexit(__tmi), 0);
#endif
//#STAY AT HOME
const int nax = 5e5 + 44;
const int L = 8;
ll rec(int a, int b, int ord) {
	// debug(imie(a), imie(b), imie(ord));
	if (ord == 0) return 0;
	int edge = 1 << ord;
	assert(a >= 0 && a < edge);
	assert(b >= 0 && b < edge);
	int half = edge / 2;
	ll siz = 1ll << (2 * (ord - 1));
	if (a < half && b < half) return rec(b, a, ord - 1);
	if (a < half && b >= half) return siz + rec(a, b - half, ord - 1);
	if (a >= half && b >= half) return 2 * siz + rec(a - half, b - half, ord - 1);
	if (a >= half && b < half) return 3 * siz + rec(half - b - 1, half - (a - half) - 1, ord - 1);
	assert(false);
}
ll cast(tuple <int, int, int> a) {
	auto [first, second, _] = a;
	swap(first, second);
	return rec(first, second, 20);
}
bool cmp(tuple <int, int, int, ll> a, tuple <int, int, int, ll> b) {
	return get<3>(a) < get<3>(b);
}
int a[nax];
int cou[nax];
int ans[nax];
int diffs = 0;
void add(int x) {
	if (cou[x] == 0) diffs++;
	cou[x]++;
}
void rem(int x) {
	cou[x]--;
	if (cou[x] == 0) diffs--;
}
int dist(tuple <int, int, int> a, tuple <int, int, int> b) {
	auto [l1, r1, _] = a;
	auto [l2, r2, _] = b;
	if (l1 > r2 || r2 < l1) return r1 - l1 + r2 - l2 + 2;
	return abs(l1 - l2) + abs(r1 - r2);
}
ll hilbert(int a, int b) {
	// debug(imie(a), imie(b));
	return rec(a, b, 19);
}
int main() {
	int n, q;
	scanf("%d%d", &n, &q);
	for (int i = 1; i <= n; ++i) scanf("%d", a + i);
	vector <tuple <int, int, int, int> > qs(q);
	REP(i, q) {
		int l, r;
		scanf("%d%d", &l, &r);
		qs[i] = {l, r, i, rec(l, r, 19)};
	}
	sort(ALL(qs), cmp);
	auto [l, r, q0, _] = qs[0];
	debug(imie(qs));
	for (int i = l; i <= r; ++i) add(a[i]);
	ans[q0] = diffs;
	for (int i = 1; i < q; ++i) {
		auto [l0, r0, _, __] = qs[i - 1];
		auto [l, r, ind, __] = qs[i];
		if (r < l0 || l > r0) {
			for (int j = l0; j <= r0; ++j) rem(a[j]);
			for (int j = l; j <= r; ++j) add(a[j]);
		}
		else {
			while (l < l0) add(a[--l0]);
			while (l > l0) rem(a[l0++]);
			while (r < r0) rem(a[r0--]);
			while (r > r0) add(a[++r0]);
		}
		ans[ind] = diffs;
	}
	REP(i, q) printf("%d\n", ans[i]);
}
//#STAY AT HOME