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.Scanner;
import java.math.*;
public class Probe {



	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner inp = new Scanner (System.in);
		int n = inp.nextInt();
		 int t = inp.nextInt();
		
		 // BigInteger
		 BigInteger ansN, N,two,  four, six, eight, yot;
		 N = new BigInteger ("10");
		 two = new BigInteger ("2");
		 four = new BigInteger ("4");
		 six = new BigInteger ("6");
		 eight = new BigInteger ("8");
		 yot = new BigInteger ("7");
		 
		 if (n == 1 )
		 {
			 if (t<10)
			 System.out.println(t);
			 else 
				 System.out.println("-1");
		 }
		 
		 else
		 {
		 
			 int exponent = n - 1;
		 
			 ansN = N.pow(exponent);
		  
			 if (  t == 3 || t == 2)
			 {
				 ansN = ansN.add(two);
				 System.out.println(ansN);
		
			 }
			 
			 if (t == 5 || t == 10)
			 {
			
				 System.out.println(ansN);
			
			 }
		
			 if (t == 9)
			 {
				 ansN = ansN.add(eight);
				 System.out.println(ansN);
		
			 }
			 
		
			 if (t == 4)
			 {
				 ansN = ansN.multiply(four);
				 System.out.println(ansN);
			
			 }
			 
			 if (t == 6)
			 {
				 ansN = ansN.multiply(six);
				 System.out.println(ansN);
			
			 }
			
			 if (t == 8)
			 {
				 ansN = ansN.multiply(eight);
				 System.out.println(ansN);

			 }
		
			 if (t == 7)
			 {
				 ansN = ansN.multiply(yot);
				 System.out.println(ansN);
			 }
		 }
	}
		
		

}