Problem: Olesya loves numbers consisting of n digits, and Rodion only likes numbers that are divisible by t. Find some number that satisfies both of them.

Your task is: given the n and t print an integer strictly larger than zero consisting of n digits that is divisible by t. If such number doesn't exist, print  - 1.

Input

The single line contains two numbers, n and t (1 ≤ n ≤ 100, 2 ≤ t ≤ 10) — the length of the number and the number it should be divisible by.

Output

Print one such positive number without leading zeroes, — the answer to the problem, or  - 1, if such number doesn't exist. If there are multiple possible answers, you are allowed to print any of them.

Examples

Input

3 2


Output

712

Solution (in JAVA):

Solution:
import java.util.Scanner;

public class MainScreen {
    public static void main(String[] args) {
    	Scanner scan=new Scanner(System.in);
    	int n=scan.nextInt();
    	int t =scan.nextInt();
    	String b="";
    	char a ='0';
    	if(t<10) {
        	b =t+"";

    	for(int i=1;i<n;i++) {

    		b =b +a;
    	}
    	}
    	else {
	    	 b ="1";

    		for(int i=1;i<n;i++) {

        		b =b +a;
        	}
    	}
    	if (n==1&&t==10) {
    		System.out.println("-1");

    	}
    	else
        		System.out.println(b);
        		System.exit(0);
        		
        
            }
     
}