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)

class BIT:
    def __init__(self, n):
        self.n = n
        self.data = [0]*(n+1)
 
    def to_sum(self, i):
        s = 0
        while i > 0:
            s += self.data[i]
            i -= (i & -i)
        return s
 
    def add(self, i, x):
        while i <= self.n:
            self.data[i] += x
            i += (i & -i)
 
    def get(self, i, j):
        return self.to_sum(j)-self.to_sum(i-1)

import sys
input = sys.stdin.readline
N,Q = map(int,input().split())
C = list(map(int,input().split()))
#print(C)
LR = []
ans = [0 for _ in range(Q)]
for i in range(Q):
  temp= list(map(int,input().split()))
  LR.append((temp,i)) #クエリとID
LR.sort(key=lambda x : x[0][1]) #右端で昇順にソート
#print(LR)
CMAX = max(C)
Tree = BIT(N)
last = [-1 for _ in range(CMAX)] #色を0index
left,right = LR[0][0]
for j in range(right):
  mae = last[C[j]-1]
  last[C[j]-1] = j
  if mae !=-1:
    Tree.add(mae+1,-1) #BITは1から
  Tree.add(last[C[j]-1]+1,1) #BITは1から
  #print(Tree.get(left,right))
#print(last)
D = []
#for i in range(1,N+1):
#  detemp = Tree.get(i,i)
#  D.append(detemp)
#print(D)

temp = Tree.get(left,right)
ID = LR[0][1]
ans[ID] = temp
lastright = right  
#print(Tree.get(left,right))
for i in range(1,Q):
  left,right = LR[i][0]
  #print(right,lastright)
  if lastright < right:
    for j in range(lastright,right):
      mae = last[C[j]-1]
      last[C[j]-1] = j
      #print(C[j],mae,j,last[C[j]-1] )
      if mae !=-1:
        #rint(C[j],"A")
        Tree.add(mae+1,-1) #BITは1index
      Tree.add(j+1,1) #BITは1index
  temp = Tree.get(left,right)
  ID = LR[i][1]
  ans[ID] = temp
  lastright = right
  #print(last)


print(*ans,sep="\n")