#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int main()
{
    bool a=1;
    int n,j;
    cin>>n;
    for(int i=2;i<=n/2;i++)
    {
        a=0;
        if(i%2==0)continue;
        for(j=2;j<=sqrt(i);j++)
            if(i%j==0){a=1;break;}
        if(a==0&&n%i==0)
        {
            for(j=2;j<=sqrt(n/i);j++)
                if((n/i)%j==0){a=1;break;}
            if(a==0){cout<<max(i,n/i);return 0;}
        }
    }
    return 0;
}