我还以为得用埃式筛法。。。

#include<iostream>
#include<stdio.h>
using namespace std;
typedef long long ll;
const ll MAXN=3000000;
bool pm[MAXN];
void init(){
    for(ll i=2;i<=MAXN;i++) if(!pm[i]) for(ll j=i*i;j<=MAXN;j+=i) pm[j]=true;
    return;
}
int main(){
    ll n;
    init();
    while(cin>>n){
        if(n==0) break;
        if(n<=4||n%2==1) cout<<"Goldbach's conjecture is wrong.\n";
        else{
            for(ll i=2;i*2<=n;i++){
                if((!pm[i])&&(!pm[n-i])){
                    printf("%d = %d + %d\n",n,i,n-i);
                    break;
                }
            }
        }
    }
    return 0;
}