拆分素数和

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <iostream>
using namespace std;

int isok(int x)
{
    double xx = (double)x;
   for(int i = (int)sqrt(xx); i > 1; i--)
     if(x%i == 0)return  0;
   return 1;
}

int main()
{
    int n;
    while(scanf("%d", &n) != EOF && n)
    {
        int x;
        int ans = 0;

        for(int i = 2; i < n/2; i++)
        {
            if(isok(i) && isok(n-i))
                ans++;
        }
        printf("%d\n", ans);
    }
    return 0;
}