import java.util.Scanner;
public class Chikanshori {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner s = new Scanner(System.in);
		long N = s.nextLong();
		s.close();
		boolean tof = true;
		int root = (int)Math.sqrt(N);
		if(N % 3 != 0 &&N % 4 == 0){
			N = 4;
		}else if(N % 2 == 0){
			N /= 2;
		}
		
		int[] prime = new int[root+1];
		prime[0] = 1;
		prime[1] = 1;
		for(int i = 3;i <=root;i++){
			if(prime[i] == 0){
				for(int j = 1;j*i <= root;j++){
					prime[j*i] = 1;
				}
				if(N % i == 0){
					System.out.println(i);
					tof = false;
					break;
				}
			}
		}
		if(tof){
			System.out.println(N);
		}

	}

}