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.math.BigInteger;
import java.util.Scanner;

public class olesyaandrodion {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
	//	BigInteger a = new BigInteger("10000");
		Scanner scan = new Scanner(System.in);
		int length = scan.nextInt();
		int div = scan.nextInt();
		if (length == 1 && div == 10) {
			System.out.println("-1");
		}
		else {
			System.out.print(div);
			if (div==10) {
				for (int i =  0; i < length-2; i++) {
					System.out.print(0);
				}
				
			}
			else {
				for(int i = 0 ; i<length-1  ; i ++) {
					System.out.print(0);
				}
			}
		}

	}
}