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;

public class CFOlaRod {

	public static void main(String[] args) throws  IOException {
		// TODO Auto-generated method stub
		BufferedReader buff = new BufferedReader(new InputStreamReader(System.in));
        String[] inputs =  buff.readLine().split(" ");
        String result = "";
        int pow =  Integer.parseInt(inputs[0]);
        int div = Integer.parseInt(inputs[1]);
        if(div!=10){
        	for(int i=0;i<pow;i++){
        		result = result+ div;
        	}
        }
        else if(pow>1){
        	result = "1";
        	for(int i=0;i<pow-1;i++){
        		result = result+ 0;
        	}
        }
        else{
        	result = "-1";
        }
        System.out.println(result);
	}

}