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 Main {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int t = scanner.nextInt();

        String value = "1";
        for(int x=1; x<n; x++){
            value += "0";
        }
        BigInteger tmp = new BigInteger(value);

        for(int x=0; x<=50; x++){
            if(tmp.mod(BigInteger.valueOf(t)).equals(BigInteger.ZERO)){
                String ans = tmp.toString();
                if(ans.length() != n){
                    System.out.println("-1");
                    return;
                }
                System.out.println(tmp.toString());
                return;
            }
            tmp = tmp.add(BigInteger.ONE);
        }

        System.out.println("-1");
    }
}