import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final long N = sc.nextLong();
		
		long min_value = N;
		for(long i = 2; i * i <= N; i++){
			if(N % i == 0){
				if(i == 2){
					min_value = Math.min(min_value, N / i);
				}else{
					min_value = Math.min(min_value, (Math.min(i, N / i)));
				}
			}
		}
		
		System.out.println(min_value);
	}

}