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 (3.4.3) (judge verdict: Accepted)

import sys
input=sys.stdin.readline
from bisect import bisect_left, bisect_right

Q=int(input())
llr=[]
maxr=1
for i in range(Q):
    l,r=map(int,input().split())
    if r>maxr:
        maxr=r
    llr.append([l,r])
def isprime(n):
    if n==1:
        return 0
    m=int(n**(1/2))
    for i in range(2,m+1):
        if n%i==0:
            return 0
            break
    return 1
l2017=[]
for i in range(1,maxr+1,2):
    if isprime(i) and isprime((i+1)/2):
        l2017.append(i)
for i in range(Q):
    il=bisect_left(l2017,llr[i][0])
    ir=bisect_right(l2017,llr[i][1])
    print(ir-il)