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

public class OlyesyaAndRodion {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String[] info = in.nextLine().split(" ");
        int n = Integer.parseInt(info[0]); // n digits long number
        BigInteger t = new BigInteger(info[1]); // number has to be divisible by t (has to be big integer b/c it used with another big integer)
        String initialNum = "1";
        BigInteger answer = new BigInteger("0");
        for(int i = 1; i < n; i++){
            initialNum += "0";
        }
        BigInteger num = new BigInteger(initialNum);
        boolean isDivisibleByt = false;
        while(num.toString().length() == n){
            if((num.mod(t)).equals(new BigInteger("0"))){
                isDivisibleByt = true;
                answer = num;
                break;
            }
            num = num.add(new BigInteger("1"));
        }
        if(isDivisibleByt){
            System.out.println(answer);
        }
        else {
            System.out.println(-1);
        }
    }
}