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)

class BIT:
  def __init__(self, n):
    self.n = n
    self.data = [0]*(n+1)
    self.el = [0]*(n+1)
  def sum(self, i):
    s = 0
    while i > 0:
      s += self.data[i]
      i -= i & -i
    return s
  def add(self, i, x):
    # assert i > 0
    self.el[i] += x
    while i <= self.n:
      self.data[i] += x
      i += i & -i
  def get(self, i, j=None):
    if j is None:
      return self.el[i]
    return self.sum(j) - self.sum(i)

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

Qs = []
for i in range(Q):
  l,r = map(int, input().split())
  Qs.append((i,l,r))
  
Qs.sort(key=lambda x:x[2])

ans = [-1]*Q
dic = {}
b = 1
bt = BIT(N)

for i,l,r in Qs:
  st = set()
  for j in range(b,r+1):
    if Cs[j] in dic:
      bt.add(dic[Cs[j]],-1)
    st.add(Cs[j])
    dic[Cs[j]] = j
  for s in st:
    bt.add(dic[Cs[j]], 1)
  ans[i] = bt.get(l-1,r)
  b = r + 1
  
for i in range(Q):
  print(ans[i])