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.IOException;
import java.io.InputStreamReader;

/**
 *
 * @author brown
 */
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;

public class Missbo {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] entrada = br.readLine().split(" ");
        int n=Integer.parseInt(entrada[0]), t=Integer.parseInt(entrada[1]);
        String num = "1";
        for (int i = 1; i < n; i++) {
            num+="0";
        }
        String num2="1";
        for (int i = 0; i < n; i++) {
            num2+="0";
        }
        BigDecimal bigdick = new BigDecimal(num);
        BigDecimal jajajas = new BigDecimal(entrada[1]);
        BigDecimal TheBigDickPlus = new BigDecimal(num2);
        boolean papu = false;
        while(!isMoreThanBigDick(bigdick, TheBigDickPlus)){
            if(isMultipleOf(bigdick, jajajas)){
                papu = true;
                break;
            }
            bigdick = bigdick.add(new BigDecimal("1"));
        }
        if(papu)
            System.out.println(bigdick);
        else
            System.out.println("-1");
    }
    public static boolean isMultipleOf(final BigDecimal multiple, final BigDecimal base)
{
    if (multiple.compareTo(base) == 0)
        return true;

    try
    {
        multiple.divide(base, 0, BigDecimal.ROUND_UNNECESSARY);
        return true;
    }
    catch(ArithmeticException e)
    {
        return false;
    }
}
    public static boolean isMoreThanBigDick(final BigDecimal multiple, final BigDecimal base){
        if (multiple.compareTo(base) == 0 || multiple.compareTo(base) == 1)
            return true;
        else
            return false;
    }
}