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)

BIT = [0] * ((1 << 19) + 1)
def add(i, x):
    while i <= (1 << 19):
        BIT[i] += x
        i += i & -i
def query(i):
    res = 0
    while i > 0:
        res += BIT[i]
        i -= i & -i
    return res
n, q = map(int, input().split())
c = list(map(int, input().split()))
Q = [[] for i in range(n)]
for i in range(q):
    l, r = map(int, input().split())
    Q[r - 1].append([l - 1, i])
l = [-1] * n
a = [-1] * q
add(1, n)
for i in range(n):
    add(l[c[i] - 1] + 2, -1)
    add(i + 2, 1)
    l[c[i] - 1] = i
    for j in Q[i]:
        a[j[1]] = query(1 << 19) - query(j[0] + 1)
print(*a, sep="\n")