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.*;
public class cpsolve {
    public static void main(String[] args){
        Scanner in=new Scanner(System.in);
        int n=in.nextInt();
        int k=in.nextInt();
        if(n==1 && k==10){
            System.out.println(-1);
        }
        else if(k==10){
            System.out.print(1+"");
            for(int i=0;i<n-1;i++){
                System.out.print(0+"");
            }
        }
        else{
            for(int i=0;i<n;i++){
                System.out.print(k+"");
            }
        }
        System.out.println();

    }
}