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 PyPy3 (7.3.0) (judge verdict: Time Limit Exceeded)

import sys
input = sys.stdin.readline
class segtree:
    ## define what you want to do ,(min, max)
    

    def __init__(self,n):
        self.n = n
        self.tree = [[]]*(2*n)
        
    def build(self, list):
        for i,x in enumerate(list,self.n):
            d = set()
            d.add(x)
            self.tree[i] = d
            
        for i in range(self.n-1,0,-1):
            self.tree[i] = self.tree[i<<1]|self.tree[i<<1 | 1]

    ## take the value of [l,r) 
    def get(self,l,r):
        l += self.n
        r += self.n
        res = set()

        while l < r:
            if l & 1:
                res |= self.tree[l]
                l += 1
            if r & 1:
                res |= self.tree[r-1]
            l >>= 1
            r >>= 1
        return len(res)

n,q = map(int,input().split())
c = list(map(int,input().split()))

seg = segtree(n)
seg.build(c)

for i in range(q):
    l,r = map(int,input().split())
    print(seg.get(l-1,r))