import java.util.*;

public class Main {
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		
		long ans = n;
		for(long i=2;i*i<=n;i++){
			if(n%i==0){
				if(i>2){
				ans=Math.min(ans, i);
				}
				else if(n/i>2){
					ans=Math.min(ans, n/i);
				}
			}
		}
		System.out.println(ans);
	}
}