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;
import java.util.Arrays;
public class e {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int t = in.nextInt();
		in.close();
        if(t!=10){
	        for(int i=1;i<=n;i++){
			    System.out.print(t);
		    }
        } else {
        	if(n>1){
        		System.out.print(1);
        		for(int i=1;i<n;i++){
    			    System.out.print(0);
    		    }
        	} else {
        		System.out.print(-1);
        	}
        }
		
		

		
	}
}