yasuo👀️

#include <iostream>
bool zisu(int x){
    for(int i=2;i*i<=x;i++)if(x%i==0)return false;
    return true;}
int main(){
    int q,ans;std::cin>>q;ans=0;
    for(int i=2;i<=q;i++)if(zisu(i)&&zisu(q-i))ans=std::max(ans,i*(q-i));
    std::cout<<ans<<"\n";return 0;}