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.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigInteger;

public class A584 {
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        String[] string = reader.readLine().split(" ");

        int n = Integer.parseInt(string[0]);
        int t = Integer.parseInt(string[1]);


        if(n == 1) {
            if(t == 10) {
                System.out.println("-1");
                System.exit(0);
            } else {
                System.out.println(t);
                System.exit(0);
            }
        }


        if(t == 2 || t == 5 || t == 10) {
            BigInteger res = BigInteger.valueOf(1);

            for (int i = 0; i < n - 1; i++) {
                res = res.multiply(BigInteger.valueOf(10));
            }

            System.out.println(res);
        }

        if(t == 3 || t == 4 || t == 6 || t == 7 || t == 8 || t == 9) {
            BigInteger res = BigInteger.valueOf(1);

            for (int i = 0; i < n - 1; i++) {
                res = res.multiply(BigInteger.valueOf(10));
            }

            res = res.multiply(BigInteger.valueOf(t));

            System.out.println(res);
        }
    }
}