poj 2909

#include <iostream>#define MAXN 1<<15using namespace std;int prime[MAXN];//为0代表是素数int findPrime(){    //先打出素数表    prime[0]=prime[1]=1;    int i,j;    for(i=2;i<MAXN;i++)    {        if(prime[i]==0)        {            for(j=2*i;j<MAXN;j+=i)                prime[j]=1;        }    }    return 0;}int main() {    //freopen("input.txt","r",stdin);    findPrime();    int n;    while ( cin>>n ,n ) {        int count = 0;        for(int i=2;i<=n/2;++i) {            if( !prime[i] && !prime[n-i] )                count++;        }        cout<<count<<endl;    }    return 0;}