#include<stdio.h>
main()
{
    int a,b,i,x, flag_a,flag_b;
    scanf("%d",&x);
    for(a=2;a<=a-1;a++)
    {
        b=x-a;
        flag_a=1;
        for(i=2;i<=a-1;i++)
        {
            if(a%i==0)
            {
                flag_a=0;
                break;
            }
        }
        if(flag_a==1)
        {
            flag_b=1;
            for(i=1;i<=b-1;i++)
            {
                flag_b=0;
                break;
            }
        }
        if(flag_b==1)
            printf("%d=%d+%d",x,a,b);
    }
}
大家看看哪有错？题目是任意输入一个偶数，求它的2
个素数之和！