#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <algorithm>
#include <cstdlib>
#include <ctime>
#include <cstdio>
#include <functional>
#include <set>
#include <sstream>
#include <map>
#include <queue>
#include <stack>

using namespace std;

typedef vector<double> vec;
typedef vector<vec> mat;

int main()
{
	long long n;
	cin>>n;
	
	for(long long i=3;i*i<=n;i++){
		if(n%i==0){
			cout<<i<<endl;
			return 0;
		}
	}

	cout<<n<<endl;	
    return 0;
}