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 cf3 {
public static void main(String[] args) throws IOException {
    BufferedReader bf = new BufferedReader (new InputStreamReader(System.in)); 
    String[] l = bf.readLine().split(" ");
    if(l[1].length()>Integer.parseInt(l[0])){
        System.out.println(-1);
    }
    else{
    System.out.print(l[1]); 
    for(int i= Integer.parseInt(l[0])-l[1].length(); i>0; i--){
        System.out.print(0);
    }
    }
    //System.out.println((long)(Integer.parseInt(l[1]) * Math.pow(10, Integer.parseInt(l[0]))));
    
    
    
}
}