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 SegTreeLayer:
    def __init__(self, segsize, function, upper_layer=None, lower_layer=None):
        self.data = []
        self.segsize = segsize
        self.function = function
        self.upper_layer = upper_layer
        self.lower_layer = lower_layer

    def update(self, i, value):
        self.data[i] = value

        if not self.upper_layer: return
        v_upper = vi = self.data[i]
        
        j = i-1 if i&1 else i+1
        if j<len(self.data):
            vj = self.data[j]
            v_upper = self.function(vi, vj)
            
        self.upper_layer.update(i//2, v_upper)

    def query(self, ibgn, iend):
        if ibgn%self.segsize==0 and iend-ibgn==self.segsize:
            return self.data[ibgn//self.segsize]

        imid = (ibgn//self.segsize)*self.segsize + self.segsize//2
        if iend<=imid or imid<=ibgn: return self.lower_layer.query(ibgn, iend)
        return self.function(
            self.lower_layer.query(ibgn, imid),
            self.lower_layer.query(imid, iend)
        )

    def extend(self, add, fill):
        self.data.extend([fill]*add)
        ndata = len(self.data)
        ndata_upper_new = (ndata+1)//2 if ndata>1 else 0
        
        if not self.upper_layer and ndata_upper_new>0:
            self.upper_layer = SegTreeLayer(
                self.segsize*2, self.function, lower_layer=self)

        if self.upper_layer:
            ndata_upper_now = len(self.upper_layer.data)
            return self.upper_layer.extend(ndata_upper_new - ndata_upper_now, fill)

        return self

N, Q = map(int, input().split())
C = list(map(int, input().split()))
LR = sorted([[q]+list(map(int, input().split())) for q in range(Q)], key=lambda x:x[2])

bottom = SegTreeLayer(1, lambda x,y: x+y)
top = bottom.extend(N, 0)
exit()

I = [None]*(N+1)
i = 0
ans = [None]*Q
for q, l, r in LR:
    while i<r:
        bottom.update(i, 1)
        
        c = C[i]
        i_old = I[c]
        if i_old is not None: bottom.update(i_old, 0)
        
        I[c] = i
        i+=1
    ans[q] = top.query(l-1,top.segsize)

for a in ans:
    print(a)