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;

/**
 *
 * @author VMCUONG
 */
public class Problem584A {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), t = sc.nextInt(); 
        BigInteger ret = BigInteger.TEN.pow(n-1), lim = BigInteger.TEN.pow(n),
                mod = BigInteger.valueOf(t);
        while(ret.compareTo(lim) == -1){
            if(ret.mod(mod).signum() == 0){
                System.out.println(ret);
                System.exit(0);
            }
            ret = ret.add(BigInteger.ONE);
        }
        
        System.out.println("-1");
    }
}