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: Wrong Answer)

import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
N,Q = map(int,readline().split())

BIT = [0]*(N+1)

def BIT_query(idx):
    res_sum = 0
    while idx > 0:
        res_sum += BIT[idx]
        idx -= idx&(-idx)
    return res_sum

def BIT_update(idx,x):
    while idx <= N:
        BIT[idx] += x
        idx += idx&(-idx)
    return

c = [-1]+list(map(int,readline().split()))
print(c)
lastAppeared = [-1]*(N+1)
ans = [0]*Q
queries = []
lr = list(map(int,read().split()))
print(lr)
for q in range(Q):
    queries.append(lr[2*q+1]*10**12+lr[2*q]*10**6+q)
queries.sort()

curR = 0
for i in range(Q):
    query = queries[i]
    r = query//10**12
    query %= 10**12
    l = query//10**6
    q = query % 10**6
    while curR < r:
        curR += 1
        new = c[curR]
        last = lastAppeared[new]
        if last != -1:
            BIT_update(last,-1)
        lastAppeared[new] = curR
        BIT_update(curR,1)
    ans[q] = BIT_query(r)-BIT_query(l-1)
for i in range(Q):
    print(ans[i])