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: Time Limit Exceeded)

class Bit:
    def __init__(self, n):
        self.size = n
        self.tree = [0] * (n + 1)

    def sum(self, i):
        s = 0
        while i > 0:
            s += self.tree[i]
            i -= i & -i
        return s

    def add(self, i, x):
        while i <= self.size:
            self.tree[i] += x
            i += i & -i


def main():
    N, Q = (int(i) for i in input().split())
    C = [int(i) for i in input().split()]
    Query = [([int(i) for i in input().split()], j) for j in range(Q)]
    Query.sort(key=lambda p: p[0][1])
    lastappend = [0]*(N+1)
    bit = Bit(N)

    for i, a in enumerate(C, start=1):
        if i <= Query[0][0][1]:
            lastappend[a] = i
    for la in lastappend[1:]:
        if la != 0:
            bit.add(la, 1)
    pre = Query[0][0][1]
    ans = []
    for (le, ri), j in Query:
        if pre <= N and pre < ri:
            for i in range(pre+1, ri+1):
                pre_i = lastappend[C[i-1]]
                if pre_i != 0:
                    bit.add(pre_i, -1)
                lastappend[C[i-1]] = i
                bit.add(i, 1)
            pre = ri
        ans.append((j, bit.sum(ri) - bit.sum(le-1)))
    ans.sort()
    for _, a in ans:
        print(a)


if __name__ == '__main__':
    main()