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.math.BigInteger;
import java.util.Scanner;

public class ProblemA {
    public static void main (String[] args) throws java.lang.Exception
    {
        int n, t;
        Scanner scn = new Scanner(System.in);
        n = scn.nextInt();
        t = scn.nextInt();
        String str = "1";
        while(--n > 0){
            str = str + "0";
        }
        BigInteger res = new BigInteger(str);
        BigInteger tInt = new BigInteger(String.valueOf(t));
        
        if(t == 0){
            System.out.print(-1);
        } else {
            
            if(res.mod(tInt).compareTo(new BigInteger("0")) != 0){
                BigInteger md = res.mod(tInt);
                res = res.add(tInt.subtract(res.mod(tInt)));
                if(res.compareTo(new BigInteger(str + "0")) >= 0){
                    res = res.subtract(tInt.subtract(md));
                    res = res.subtract(md);
                    if(res.compareTo(new BigInteger(str)) < 0){
                        System.out.print(-1);
                        return;
                    }
                }
            }
            
            System.out.print(res.toString());
        }
    }
}