#include<stdio.h>
int main()
{
int su(int p);
int n,i,p=0,s=0;
scanf("%d",&n);
while(n<3||n%2==1)
{
printf("请重新输入");
scanf("%d",&n);
} for(i=3;i<n/2;i=i+2)
{
p=0;
if(su(i))
p++;
if(su(n-i))
p++;
if(p==2){s++;
printf("%d=%d+%d\n",n,i,n-i);}
}
printf("有%d对\n",s);
return 0;
} int su(int p)
{
int j,t=1;
for(j=2;j<p;j++)
if(p%j==0)t=0;
return t;
}