#include<bits/stdc++.h>
using namespace std;
bool zs(int a)
{
    int i;
    for(i=2;i<=sqrt(a);i++)if(a%i==0)return 0;       
    return 1;
}
int main()
{
	int n,p,i;
	cin>>n;
	if(n%2==0)cout<<n/2;
	else for(i=n-1;i>=3;i--)if(n%i==0&&zs(i)&&zs(n/i)){cout<<i;exit(0);}
	return 0;
}