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 OlesyaandRodion {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scan = new Scanner (System.in); 
		
		int n = scan.nextInt(); 
		
		int t = scan.nextInt(); 
		
		if(n==1&&t==10){
			
			System.out.println(-1);
			
		}else if(n==1){
			
			System.out.print(t);
			
		}else{
			
			if(t==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(t);
					
				}
				
			}
			
		}

	}

}