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>
#define rep(i,n) for(int i=0; i<(n); i++)
#define FOR(i,a,n) for(int i=(a); i<(n); i++)
#define all(v) v.begin(), v.end()
#define fi first
#define se second
#define sz(x) int(x.size())
using namespace std;
using ll = long long;
using P = pair<int ,int>;
const int INF = 1001001001;
const int MOD = 1000000007;
template<class T> inline bool chmax(T &a, T b) { if (a<b) {a=b; return 1;} return 0;}
template<class T> inline bool chmin(T &a, T b) { if (b<a) {a=b; return 1;} return 0;}

#ifdef _DEBUG
#include "debug.h"
#else
#define debug(...)
#define print(...)
#endif

int main() {
    int n, q; cin >> n >> q;
    vector<int> a(n);
    rep(i, n) cin >> a[i];
    vector<int> b(n+2, 0);
    set<int> st;
    rep(i, n) {
        st.insert(a[i]);
        b[i+1] = sz(st);
    }
    b[n+1] = b[n];
    debug(b);
    vector<int> c(n+2, 0);
    st.clear();
    rep(i, n) {
        st.insert(a[n-i-1]);
        c[n-i] = sz(st);
    }
    c[0] = c[1];
    debug(c);
    rep(i, q) {
        int l, r; cin >> l >> r;
        // l--; r--;
        if (l==r) cout << 1 << endl;
        else cout << max(b[r]-b[l-1], c[l]-c[r+1]) << endl;
    }
}