#include<iostream> #include<cmath> using namespace std; bool sushu(int n){ int j; if(n<=1) return False; for(j=2;j<=sqrt(n);j++){ if(n%j==0){ return False; } } return True; } int main(){ int i=0,j,num=0,n1=2,n2,max=0; int arr[20001]={0}; cin>>num; while(n1<=num/2){ n2=num-n1; if(sushu(n2)&&sushu(n1)){ if(max=n1*n2) max=n1*n2; } n1++; } cout<<max<<endl; return 0; }