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