#include <bits/stdc++.h>
using namespace std;
int main() {
// your code goes here
long long n,t=1;
cin>>n;
if(n<=3){
t=0;
}
for(int i=2;i<n;i+=2){
if(n%i==0){
t*=i;
}
}
if(t==1){
cout<<0,exit(0);
}
cout<<t;
return 0;
}
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