import java.io.*;
import java.util.*;
public class Main {
	public static void main(String args[]) throws Exception {
		Scanner in = new Scanner(System.in);
		long a = in.nextLong(), b = in.nextLong();
		long fr = 1;
		for(int i = 1; i <= b; i ++){
		    fr = fr * a;
		}
		if(fr >= 1000000000){
		    System.out.println("-1");
		}
		else{
		    System.out.println(fr);
		}
	}
}