> #include <stdio.h>
> 
> char flag[1000001]={'\0'};
> void creat()
> {
>      unsigned long i,j;
>      for(i=2;i<1000001;i++)
>      {if(flag[i]=='\0')
>      {for(j=i;j*i<1000001;j++)
>      flag[i*j]='1';}}
> }
> int main()
> {
>       unsigned long num,k;
>     
>     
>     creat();
>   
>     
>     scanf("%lu",&num);
>     while(num>0)
>     {
>                 for(k=3;k<=num/2;k++)
>                 {
>                                       if((flag[k]=='\0')&&(flag[num-k]=='\0'))
>                                       {printf("%lu = %lu + %lu\n",num,k,num-k);
>                                       break;}
>                 }
>                 if(k>num/2)
>                 printf("Goldbach's conjecture is wrong.");
>                 scanf("%lu",&num);
>     }
>     return 0;
> }