#include <vector>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>
#include <utility>
#include <functional>
#include <sstream>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
#include <cassert>
using namespace std;
inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vs;
typedef pair<int, int> pii;
typedef long long ll;
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(),(a).rend()
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define EACH(t,i,c) for(t::iterator i=(c).begin(); i!=(c).end(); ++i)
const double EPS = 1e-13;
const double PI  = acos(-1.0);


int p[1<<15]={1,1};
set<int> primes;
int main(){
	FOR(i,2,1<<15){
		if(!p[i]){
			primes.insert(i);
			for(int j=i;j<(1<<15);j+=i){
				p[j]=1;
			}
		}
	}

	int n;
	while(cin>>n,n){
		int ans=0;
		FOR(i,2,n/2+1){
			if(EXIST(primes,i)&&EXIST(primes,n-i)){
				ans++;
			}
		}
		cout<<ans<<endl;
	}

}