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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<stdio.h>
int main()
{
    int a,b,count,i,j,c,flag,n;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        count=0;
        scanf("%d %d",&a,&b);
        for(j=a;j<=b;j++)
        {

            flag=0;
            for ( c = 2 ; c <= j-1 ; c++ )
            {
            if ( j%c == 0 )
            {
                flag=1;
                break;
            }
            }
            int k=(j+1)/2;
            if(flag==0)
            {
                for ( c = 2 ; c <= k-1 ; c++ )
                {
                if ( k%c == 0 )
                {
                flag=1;
                break;
                }
                }
            }
            if(flag==0)
                count++;
        }
        printf("%d\n",count);
    }
    return 0;
}