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.Scanner;

public class OlesyaandRodion {

	public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
long a=sc.nextInt();
long b=sc.nextInt();
long n=b;
long countb=0;

while(n!=0)
{
	countb++;
	n=n/10;
	
}
long count0=a-countb;
long num=b;
if(count0<0)
{
	System.out.println("-1");
}
else {
	System.out.print(b);
while(count0!=0)
{
System.out.print("0");
count0--;}
	}
	}

}