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)

I = [int(_) for _ in open(0).read().split()]
N, Q = I[:2]
C = [0] + I[2:2 + N]
LR = I[2 + N:]


class BinaryIndexedTree():
    def __init__(self, n):
        """
        constructs binary indexed tree

        Parameters
        ----------
        n : int
            maximum index value
        """
        self.n = n
        self.dat = [0] * (n + 1)

    def sum(self, i):
        """
        returns the sum of [1, i]

        Parameters
        ----------
        i : int
            right end of the interval
        """
        s = 0
        while i:
            s += self.dat[i]
            i -= i & -i
        return s

    def add(self, i, x):
        """
        adds x to i-th element

        Parameters
        ----------
        i : int
            index
        x : int
            additional value
        """
        while i <= self.n:
            self.dat[i] += x
            i += i & -i


BIT = BinaryIndexedTree(500010)

arr = [5 * 10**5 + 4] * (5 * 10**5 + 5)
RLI = sorted((lr[1], lr[0], i) for i, lr in enumerate(zip(LR[::2], LR[1::2])))
ans = [None] * Q
j = 0
for r, l, i in RLI:
    for j in range(j, r):
        j += 1
        if arr[C[j]]:
            BIT.add(arr[C[j]], -1)
        arr[C[j]] = j
        BIT.add(j, 1)
    ans[i] = BIT.sum(r) - BIT.sum(l - 1)
print('\n'.join(map(str, ans)))