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: Accepted)

import sys
input = sys.stdin.readline

n, q = map(int, input().split())
C = [0] + list(map(int, input().split()))
D = [-1]*(n+1)
A = [0]*q
U = 10**6
LR = tuple(tuple(map(int, input().split())) for _ in range(q))
W = sorted(r*U+i for i, (l, r) in enumerate(LR))
B = [0]*(n+1)
def add(i, a):
  while i <= n:
    B[i] += a
    i += i & -i
def acc(i):
  res = 0
  while i:
    res += B[i]
    i -= i & -i
  return res
temp = 1
for w in W:
  r, i = divmod(w, U)
  while temp <= r:
    c = C[temp]
    add(temp, 1)
    if D[c] != -1:
      add(D[c], -1)
    D[c] = temp
    temp += 1
  l = LR[i][0]
  A[i] = acc(r) - acc(l-1)
print(*A, sep="\n")