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.math.BigInteger;
import java.util.Scanner;

/*
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/**
 *
 * @author TheSiscoKid
 */
public class OlesyaandRodion {
        public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int O = scanner.nextInt();
        String R = String.valueOf(scanner.nextInt());
        if(O == 1 && R.equals("10")){
            System.out.println(-1);
        } else {
        BigInteger temp = (new BigInteger("10")).pow(O - 1);
        System.out.println(temp.add((new BigInteger(R)).subtract(temp.mod(new BigInteger(R)))).toString());
        scanner.close();
        }
    }
}