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 Number {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int n = input.nextInt();
        long t = input.nextInt();
        if (n == 1 && t == 10) {
            System.out.println(-1);
        } else {
            BigInteger tBig = new BigInteger(Long.toString(t));
            BigInteger firstNumber = BigInteger.TEN;
            firstNumber = firstNumber.pow(n - 1);
            BigInteger remainder =  firstNumber.mod(tBig);
            firstNumber = firstNumber.add(tBig.subtract(remainder));
            System.out.println(firstNumber);
        }
    }
}