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:
/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;
import java.math.BigInteger;

/**
 *
 * @author Mukhtar
 */
public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int b = scanner.nextInt();
        String range = "1";
        if (a == 1 && b == 10) {
        	System.out.println(-1);
        }
		else {
        for (int i = 0; i <a-1; i++) {
        	range += "0";
        }
        BigInteger rangeInt1 = new BigInteger(range);
        BigInteger rangeInt2 = new BigInteger(range+"0");
        for (BigInteger i = rangeInt1; i.compareTo(rangeInt2) < 0; i = i.add(BigInteger.ONE)) {
            if (i.mod(BigInteger.valueOf(b)).compareTo(BigInteger.ZERO) == 0) {
                System.out.println(i);
                return;
            }
        }
        System.out.println(-1);
		}
    }
}