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 Python (3.8.2) (judge verdict: Runtime Error)

from collections import defaultdict
import sys
input = sys.stdin.readline

class FenwickTree:
    def __init__(self, n):
        self.n = n
        self.dat = [0] * n
        
    def add(self, i, x):
        while i < self.n:
            self.dat[i] += x
            i += i & (-i)
    def sum(self, i):
        res = 0
        while i > 0:
            res += self.dat[i]
            i -= i & (-i)
        return res
    def rangesum(self, l, r):
        return self.sum(r) - self.sum(l-1)

N, Q = map(int, input().split())
C = [0] + list(map(int,input().split()))

ql, qid = defaultdict(list), defaultdict(list)

for i in range(Q):
    l, r = map(int, input().split())
    ql[r].append(l)
    qid[r].append(i)

A = [0] * (N+1)
ANS = [0] * (N+1)

FT = FenwickTree(N+1)

for i in range(1, N+1):
    if A[C[i]]:
        FT.add(A[C[i]], -1)
    FT.add(i, +1)
    A[C[i]] = i
    for j in range(len(ql[i])):
        ANS[qid[i][j]] = FT.rangesum(ql[i][j],i)

for ans in ANS[:Q]:
    print(ans)