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