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 Python (3.8.2) (judge verdict: Time Limit Exceeded)

import sys
input = sys.stdin.readline

N, Q = map(int, input().split())
C = list(map(int, input().split()))
LRST = []
for i in range(Q):
    l, r = map(int, input().split())
    LRST.append((l-1, 0, r-1, i))


class FenwickTree(object):
    def __init__(self, n):
        self._bit = [0] * (n+1)
        self.n = n+1
    
    def add(self, i, a):
        i += 1
        while i < self.n:
            self._bit[i] += a
            i += i & -i
    
    def sum(self, i):
        i += 1
        ret = 0
        while i > 0:
            ret += self._bit[i]
            i -= i & -i
        return ret


def solve():
    memo = [-1] * N
    for i, c in enumerate(C):
        if memo[c-1] >= 0:
            LRST.append((memo[c-1], 1, i, -1))
        memo[c-1] = i
    LRST.sort(reverse=True)
    ans =[0 for _ in range(Q)]
    ft = FenwickTree(N+1)
    for sl, typ, tr, q in LRST:
        if typ == 1:
            ft.add(tr, 1)
        else:
            ans[q] = tr - sl + 1 - ft.sum(tr)
    for a in ans:
        print(a)


if __name__ == "__main__":
    solve()