import java.io.*;

public class No312 {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		long n = Long.parseLong(br.readLine());
		
		boolean flag = false;
		long ans = n;
		for(int i = 3 ; i*i <= n ; i++){
			if(n % i == 0){
				ans = i;
				flag=true;
				break;
			}
		}
		if(!flag && n%2 == 0 && n!= 4) ans = n / 2;
		
		System.out.println(ans);
	}
}