//#include<bits/stdc++.h> #include<iostream> using namespace std; bool isprime(int s){ bool f = 1; for(int i = 2;i < s;i++){ if(s % i == 0){ f = 0; break; } } return f; } int main(){ //freopen("a.in";,"r",stdin); //freopen("b.out","r",stdout); int s; cin >> s; int max = 0; for(int i = 2;i <= s / 2;i++){ if(isprime(i) && isprime(s - i)){ if(i * (s - i) > max){ max = i*(s-i); } } } cout << max << endl; return 0; }