UVa - 686 - Goldbach's Conjecture (II)

#include <iostream>
#include <cstdio>
#include <vector>
#include <cmath>
#define M 33000
using namespace std;
bool prime[M];
int main(){
    for(int i = 2; i <= sqrt(M); i++)
        if(prime[i] == 0)
            for(int j = i+i; j < M; j += i)prime[j] = 1;

    int n;
    while(cin >> n){
        if(n == 0)break;
        int m = 0, x, y;
        for(int j = 2; j < n; j++)
            if(!prime[j] && !prime[n-j])
                if((j > 1 && j <= (n/2)) && ((n-j) > 1 && (n-j) >= (n/2)))m++;
        cout << m << endl;
    }

    return 0;
}