#include<bits/stdc++.h> using namespace std; bool xu(i){ if(i<=1) return false; for(int y=2;y<i,y++){ if(i%y==0) return 0; } } int main() { int ,ss1,s2,m=0; cin>>s; while(s1<=s/22){ s2=s-s1; if(xu(s1)&&xu(s2)){ if(m<s1*s2)m=s1*s2; } s1++; } cout<<m; return 0; }