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 FenwickTree:

    def __init__(self, size):
        self.size = size
        self.array = [0]*size

    def add(self, index, value):
        while index < self.size:
            self.array[index] += value
            index += index&(-index)

    def sum(self, index):
        answer = 0
        while index > 0:
            answer += self.array[index]
            index -= index&(-index)
        return answer

    def rangesum(self, start, end):
        return self.sum(end)-self.sum(start-1)


def read_int():
    return int(input().strip())


def read_ints():
    return list(map(int, input().split(' ')))

def read_query():
    l, r = read_ints()
    return l-1, r-1

def solve():
    N, Q = read_ints()
    C = [c-1 for c in read_ints()]
    colour_to_index = [-1]*N
    queries = [read_query() for _ in range(Q)]
    answer = [-1]*Q
    queries_sorted_index = sorted(list(range(Q)), key=lambda i: queries[i][1])
    fenwick_tree = FenwickTree(N+1)
    last_r = -1
    for i in queries_sorted_index:
        l, r = queries[i]
        for j in range(last_r+1, r+1):
            colour = C[j]
            if colour_to_index[colour] != -1:
                fenwick_tree.add(colour_to_index[colour]+1, -1)
            colour_to_index[colour] = j
            fenwick_tree.add(colour_to_index[colour]+1, 1)
        answer[i] = fenwick_tree.rangesum(l+1, r+1)
        last_r = r
    print(*answer, sep='\n')


if __name__ == '__main__':
    solve()