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.*;

//Mann Shah [ DAIICT ].

public class Main { 
	
	

	public static void main(String[] Args) {
		Scanner in = new Scanner(System.in);
		int mod = 1000000007;
		
		int  n = in.nextInt();
		int t = in.nextInt();
		
		if(t==10 && n==1) {
			System.out.println("-1");
		}
		else {
			if(t==10) {
				System.out.print(t);
				for(int i=0;i<n-2;i++) {
					System.out.print("0");
				}
			}
			else {
				System.out.print(t);
				for(int i=0;i<n-1;i++) {
					System.out.print("0");
				}
			}
		}
		in.close();
	}
}