Problem:
Pair of Primes

We arrange the numbers between 1 and N (1 <= N <= 10000) in increasing
order and decreasing order like this:

1 2 3 4 5 6 7 8 9 . . . N
N . . . 9 8 7 6 5 4 3 2 1

Two numbers faced each other form a pair. Your task is to compute the number of pairs P such that both
numbers in the pairs are prime.

Input

Input contains several test cases. Each test case consists of an integer N in
one line.

Output

For each line of input, output P .

Sample Input

1
4
7
51

Output for the Sample Input

0
2
2
6

Solution in Python (judge verdict: Accepted)

import math
N=10000
prime=[1]*(N+1)
prime[0],prime[1]=0,0
for i in range(2,int(math.sqrt(N))):
    if prime[i]==1:
        j=i
        while i*j<=N:
            prime[i*j]=0
            j+=1

while True:
    try:
        n=input()
    except EOFError:
        break
    cnt=0
    for i,j in zip(prime[1:n+1],prime[1:n+1][::-1]):
        if i==j==1:
            cnt+=1
    print cnt