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 mohit_sharma{
	public static void main(String[] args){
		
		int n,t;
		Scanner input = new Scanner(System.in);
		n = input.nextInt();
		t = input.nextInt();
		
		if(n ==1 && t == 10){
			System.out.print(-1);
			return;
		}
		List<Integer> vec = new ArrayList<>();
		if(t != 10){
			vec.add(t);
			for(int i=1;i<n;i++){
				vec.add(0);
			}
		}else if( t == 10){
			vec.add(1);
			for(int i=1;i < n;i++){
				vec.add(0);
			}
		}
		
		for(int  i=0;i< n;i++){
			System.out.print(vec.get(i));
		}
	}
}