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:
// object [] array = new object[]

import org.omg.Messaging.SYNC_WITH_TRANSPORT;

import java.math.BigInteger;
import java.text.DecimalFormat;
import java.util.*;

public class acm {
    public static int[] trops;
    public static void main (String[] args) {
        Scanner scan = new Scanner(System.in);
        int a = scan.nextInt();
        int b = scan.nextInt();
        BigInteger c = new BigInteger("10");
        BigInteger d = c.pow(a -1);
        BigInteger b1 = new BigInteger(Integer.toString(b));
        if (a == 1) {
            if (b == 10) {
                System.out.println(-1);
                return;
            } else {
                System.out.println(b);
                return;
            }
        }
        System.out.println(b1.subtract(d.divideAndRemainder(b1)[1]).add(d));

    }
}