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 java {
    public static void main(String[] args) {
     
        Scanner in = new Scanner (System.in);
        int n=in.nextInt();
        int k=in.nextInt();
        if(n==1&&k<10)
            System.out.print(k);
     else if(n==1&&k==10)
             System.out.print("-1");
     else if(k!=10)
         for(int i=0;i<n;i++)
                System.out.print(k);
     else { System.out.print(k);
            for(int i=1;i<=n-2;i++)
                System.out.print("0");
     }
      
    }
    
}