#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; return 0; }