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: Runtime Error)

from operator import itemgetter
import sys
def read():
    return sys.stdin.readline().rstrip()
def main():
    N, Q = map(int, read().split())
    C = list(map(int, read().split()))
    E = []

    D = [-1] * N
    for i in range(N):
        D_i = D[C[i]]
        if D_i != -1:
            E.append((D_i, i, -1))
        D[C[i]] = i

    for i in range(Q):
        l, r = map(int, input().split())
        E.append((l - 1, r - 1, i))

    def f(tup):
        return tup[0]
    E.sort(key=f, reverse=True)

    # Binary Indexed Tree (Fenwick Tree)
    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)

    ANS = [0] * Q
    d = BIT(N)
    for e in E:
        if e[2] == -1:
            d.add(e[1], 1)
        else:
            ANS[e[2]] = e[1] - e[0] + 1 - d.sum(e[1])

    for i in range(Q):
        print(ANS[i])

if __name__ == '__main__':
    main()