//============================================================================
// Name        : Goldbach.cpp
// Author      : 
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include <stdio.h>
#include <cmath>
using namespace std;

bool isPrime[32770] = {false};

int primelist[42] = {2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181};


bool isprime(int n){
	int sqrtn = (int)sqrt(n*1.0);
	bool prime = true;
	for(int i = 3; i <= sqrtn; i += 2){
		if(n%i == 0){
			prime = false;
			break;
		}
	}
	return prime;
}

int geshu[32770] = {0};

int main() {

	for(int i = 0; i < 42; i++){
		isPrime[primelist[i]] = true;
	}
	//int cn = 0;
	for(int i = 183; i <= 32767; i += 2){
		bool res = true;
		int sqrti = (int)sqrt(i*1.0);
		for(int j = 1; j < 42; j++){
			if(primelist[j] > sqrti + 1) break;
			//cn ++;
			if(i%primelist[j] == 0){
				res = false;
				break;
			}
		}
		isPrime[i] = res;
	}
	//cout << cn << endl;
	int N;

	//cout << endl;
	while(1){
		scanf("%d", &N);
		if(N == 0) return N;
		if(geshu[N] != 0){
			//cout << geshu[N] << endl;
			printf("%d\n", geshu[N]);
			continue;
		}
		if(N%2 == 1){
			if(isPrime[N-2]) printf("1\n");
			else printf("0\n");
			continue;
		}
		int cnt = 0;
		for(int i = 2; i <= N/2; i++){
			if(isPrime[i] && isPrime[N-i]){
				cnt ++;
			}
		}
		geshu[N] = cnt;
		printf("%d\n", cnt);
	}
	return 0;
}