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)

n, q = map(int, input().split())
unit = int(n**0.5)
n_unit = (n+unit-1)//unit
c = list(map(int, input().split()))
lst = []
for i in range(q):
    li, ri = map(int, input().split())
    li -= 1; ri -= 1
    left_unit = li // unit
    lst.append([li, ri, i, -1, left_unit])
lst.sort(key=lambda x: x[1])
lst.sort(key=lambda x: x[4])

dic_lst = [{} for i in range(n_unit)]
for i in range(n):
    idx = i // unit
    if c[i] in dic_lst[idx]:
        dic_lst[idx][c[i]] += 1
    else:
        dic_lst[idx][c[i]] = 1

left_unit = -1
right_unit = -1
for i in range(q):
    li, ri = lst[i][0], lst[i][1]
    if li//unit != left_unit:
        temp = {}
        left_unit = li // unit
        right_unit = ri // unit
        for j in range(left_unit+1, right_unit):
            for key, value in dic_lst[j].items():
                if key in temp:
                    temp[key] += value
                else:
                    temp[key] = value

        now = temp.copy()
        for j in range(li, min((left_unit+1)*unit, ri+1)):
            if c[j] in now:
                now[c[j]] += 1
            else:
                now[c[j]] = 1
        for j in range(max((right_unit)*unit, li), ri+1):
            if c[j] in now:
                now[c[j]] += 1
            else:
                now[c[j]] = 1

        lst[i][3] = len(now)
    else:
        for j in range(max(right_unit, left_unit+1), ri//unit):
            for key, value in dic_lst[j].items():
                if key in temp:
                    temp[key] += value
                else:
                    temp[key] = value

        now = temp.copy()
        for j in range(li, min((left_unit+1)*unit, ri+1)):
            if c[j] in now:
                now[c[j]] += 1
            else:
                now[c[j]] = 1
        for j in range(max((right_unit)*unit, li), ri+1):
            if c[j] in now:
                now[c[j]] += 1
            else:
                now[c[j]] = 1

        lst[i][3] = len(now)

lst.sort(key=lambda x: x[2])
for i in range(q):
    print(lst[i][3])