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.*;
import java.math.*;
public class recycle {
	
	public static void main(String[] args) {
		
		Scanner qwe = new Scanner(System.in);
		
		int n = qwe.nextInt();
		BigInteger t = new BigInteger(qwe.next());
		BigInteger cur = new BigInteger(t.toString());
		while(cur.toString().length() < n){
			cur = cur.multiply(t);
		}
		
		if(cur.toString().length() > n) {
			cur = new BigInteger("-1");
		}
		
		System.out.println(cur);
		
		
		qwe.close();
		
	}

}