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.*;

/**
 *
 * @author Mido
 */
public class Test {

    /**
     * @param args the command
     */
    
    public static void main(String[] args) {
        int i,n,ans=0,t;
        Scanner sc=new Scanner(System.in);
        n=sc.nextInt();
        t=sc.nextInt();
        String s =""+t;
        i=s.length();
        for(;i<n;i++) s+='0';
        System.out.println(s.length()>n?-1:s);
    }
}