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 lololol {
	public static void main(String[]arg){
     	Scanner sc = new Scanner(System.in);
     	int x=sc.nextInt();
     	int y=sc.nextInt();
     	String s="";
     	if(x==1 && y==10 ) {
     		System.out.print(-1);
     	}else if(y==10) {
     		for(int i=0;i<x-1;i++) {
     			s=s+1+"";
     		}
     		System.out.print(s+'0');
     	}else {
     		
     		for(int i=0;i<x;i++) {
         		s=s+y+"";
         	}
         	System.out.print(s);
         	
     	}
     	
     	
	}}