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.*;

public class Solution{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        
        int n = sc.nextInt();
        int t = sc.nextInt();
        
        if(t == 10){
            if(n == 1){
                System.out.println("-1");    
            }
            else{
                String number = "";
                for(int i=1; i<n; i++){
                    number = number.concat("1");    
                }
                
                number = number.concat("0");
                
                System.out.println(number);
            }
        }
        else{
            String number = "";
            for(int i=1; i<=n; i++){
                number = number.concat(t + "");
            }
            
            System.out.println(number);
        }
    }
}