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;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.DecimalFormat;
import java.util.*;
import java.text.NumberFormat;
//import java.util.Arrays;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

public class Main {

    public static void main(String[] args) throws IOException {
        Scanner input = new Scanner(System.in);
        long len=input.nextLong();
        
        String div=input.next();
       
        if(div.length()==len){
            System.out.println(div);
        }
        else if(div.length()>len){
            System.out.println("-1");
        }
        else{//div.length<len
            for (int i = div.length(); i < len; i++) {
                div=div+"0";
            }
            System.out.println(div);
        }
    }
}