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 T5 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sca=new Scanner(System.in);
		int n,t;
		while(sca.hasNext()){
			n=sca.nextInt();
			t=sca.nextInt();
			if(t==10&&n==1){
				System.out.println(-1);
				continue;
			}
			if(t==10){
				for(int i=1;i<=n-2;i++)System.out.print(1);
				System.out.println(10);
			continue;
			}
			for(int i=1;i<=n;i++)System.out.print(t);
			
		}
	
	
	}

}