Problem:
Score : 400 points

Problem Statement

We say that a odd number N is similar to 2017 when both N and (N+1)/2 are prime.

You are given Q queries.

In the i-th query, given two odd numbers l_i and r_i, find the number of odd numbers x similar to 2017 such that l_i ≤ x ≤ r_i.

Constraints

1≤Q≤10^5

1≤l_i≤r_i≤10^5

l_i and r_i are odd.

All input values are integers.

Input

Input is given from Standard Input in the following format:

Q
l_1 r_1
:
l_Q r_Q

Output

Print Q lines. The i-th line (1≤i≤Q) should contain the response to the i-th query.

Sample Input 1

1
3 7

Sample Output 1

2

3 is similar to 2017, since both 3 and (3+1)/2=2 are prime.

5 is similar to 2017, since both 5 and (5+1)/2=3 are prime.

7 is not similar to 2017, since (7+1)/2=4 is not prime, although 7 is prime.

Thus, the response to the first query should be 2.

Sample Input 2

4
13 13
7 11
7 11
2017 2017

Sample Output 2

1
0
0
1

Note that 2017 is also similar to 2017.

Sample Input 3

6
1 53
13 91
37 55
19 51
73 91
13 49

Sample Output 3

4
4
1
1
1
2

Solution in Ruby (2.7.1) (judge verdict: Accepted)

def divisors(n)
  p = []
  2.upto((n**0.5)) do |i|
    break if i > n / i
    while n % i == 0
      p << i
      n /= i
    end
  end
  p << n if n != 1
  p
end
Q = gets.to_i
l, r = Q.times.map{gets.split.map(&:to_i)}.transpose
max = r.max
arr = Array.new(max+1,0)
1.upto(max) do |i|
  arr[i] = arr[i-1]
  if divisors(i).length == 1 && divisors((i+1)/2).length == 1
    arr[i] += 1
  end
end
Q.times do |i|
  puts arr[r[i]] - arr[l[i]-1]
end