import java.util.*;

public class Main{
	
	public static void main(String[] args)
	{
	    Scanner sc = new Scanner(System.in);

	    String input = sc.nextLine();
	    String[] inputArr = input.split(" ");
	    int a = Integer.parseInt(inputArr[0]);
	    int b = Integer.parseInt(inputArr[1]);

	    boolean bySelf = (Math.abs(a) % 100 == 0 && Math.abs(b) % 100 == 0);

	    int ans = a * b;

	    if (bySelf) {
	        ans /= 10;
	    } else {
	        if (-99999999 > ans || ans >= 99999999){
	            ans = -1;
	        }
	    }

	    String ansStr = ans == -1 ? "E" : ans+"";

	    System.out.println(ansStr);
	}
}