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.*;
import java.lang.*;

public class Main{
    public static void main(String[] args){
        Scanner scn = new Scanner(System.in);
        int n = scn.nextInt();
        int m = scn.nextInt();
        
        long r1 = (long)Math.pow(10,n-1);
        long r2 = (long)Math.pow(10,n);
        String s = "1";
        
        for(int a=1;a<n;a++){
            s += "0";
        }
        String ans = "";
        
        if(n==1){
            if(m!=10){
                System.out.println(m);
            }
            else{
                System.out.println(-1);
            }
        }
        else{
            if(m==2 || m==3 || m==6){
                ans = s.substring(0,n-1) + "2";
            }
            if(m==4){
                ans = "4" + s.substring(1,n);
            }
            if(m==5 || m==10){
                ans = s.substring(0,n);
            }
            
            if(m==8){
                ans = "8" + s.substring(1,n);
            }
            if(m==9){
                ans = s.substring(0,n-1) + "8";
            }
            if(m==7){
                ans = "7" + s.substring(1,n);
            }
            System.out.println(ans);
        }
        
        
    }
}