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.math.BigInteger;
public class hehe{
    public static void main(String args[]){
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int t = scan.nextInt();
        BigInteger output = BigInteger.valueOf(0);
        BigInteger p = BigInteger.valueOf(10);
        BigInteger min = p.pow(n-1);
        BigInteger max = p.pow(n);
        boolean cancer = true;
        while(cancer && (min.compareTo(max)) == -1 ){
            BigInteger m = min.mod(BigInteger.valueOf(t));
            if(m.equals(BigInteger.ZERO)){
                output = min;
                cancer = false;
            }
            else{
                output = BigInteger.valueOf(-1);
            }
            min = min.add(BigInteger.valueOf(1));
       }
       System.out.print(output);
         
    }
}