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 Python (3.8.2) (judge verdict: Accepted)

# エラトステネスの篩, 累積和
def make_prime_table(n):
    sieve = list(range(n + 1))
    sieve[0] = -1
    sieve[1] = -1
    for i in range(2, int(n ** 0.5) + 1):
        if sieve[i] != i:
            continue
        for j in range(i * i, n + 1, i):
            if sieve[j] == j:
                sieve[j] = i
    return sieve


max_lr = 10 ** 5

prime_table = make_prime_table(max_lr)

cs = [0] * (max_lr + 1)
for i in range(3, max_lr + 1, 2):
    j = (i + 1) // 2
    if prime_table[i] == i and prime_table[j] == j:
        cs[i] = 1
for i in range(1, max_lr + 1):
    cs[i] += cs[i - 1]

Q = int(input())
result = []
for _ in range(Q):
    l, r = map(int, input().split())
    result.append(cs[r] - cs[l - 1])
#print('\n'.join(str(i) for i in result))
print(*result, sep='\n')