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;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;

public class A_Olesya_and_Rodion {
 
    public static void main(String[] args) {
        Scanner sc= new Scanner(System.in);
        int n=sc.nextInt(), t=sc.nextInt();
        String ans="";
        
        if((int)Math.pow(10, n)-1<t){
            ans+="-1";
        }
        else if(t==10){
            for(int q=0; q<n-1; q++){
                ans+='1';
            }
            ans+='0';
        }
        else{
            for(int q=0; q<n; q++){
                ans+=t;
            }
        }
        System.out.print(ans);
        // String s1="";
        // s1=f==1?"NO":"YES";
        // System.out.println(s1);
    }
}