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 OlesyaRodion {
    
    public static void main(String[] args) {
        
        int n, t;
        String number = "";
        Scanner input = new Scanner(System.in);
        
        n = input.nextInt();
        t = input.nextInt();
        
        if((n == 1 && t == 10)) System.out.println(-1);
        
        else if(n > 1 && t == 10){
            for(int i = 0; i < n-1; i++){
                number += '1';
            }
                number += '0';
                
                System.out.println(number);
        }
        
        else{
            String temp = Integer.toString(t);
            for(int i = 0; i < n; i++){
                number += temp;
            }
            System.out.println(number);
        }
          
        
    }
    
}