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 Main
{
	public static void main(String[] args) {
		 Scanner s=new Scanner(System.in);
	    int n=s.nextInt();
	    int t=s.nextInt();
	    if(n==1 && t==10){
	        System.out.print("-1");
	    }
	    else{
	        if(t==10){
	            for(int i=0;i<n-1;++i){
	                System.out.print('1');
	            }
	            System.out.print('0');
	        }
	        else{
	            for(long i=1;i<=n;++i){
	                System.out.print(t);
	            }
	        }
	    }
	}
}