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;
public class fd { 
public static void main (String [] args) { 
Scanner scanner = new Scanner (System.in);
int a  = scanner.nextInt();
int t  = scanner.nextInt();
if (t==10) {
	if (a==1) System.out.println(-1);
	else{
	System.out.print(1);
	for (int i=1;i<a;i++) {
		System.out.print(0);
	}}
}
else {
	for (int i=0;i<a;i++) {
		System.out.print(t);
	}
}
scanner.close(); }}