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.io.*;
public class A_OlesyaAndRodion {
	public static void main(String args[])throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String str = br.readLine();
		int n = Integer.parseInt(str.substring(0, str.indexOf(" ")));
		int t = Integer.parseInt(str.substring(str.indexOf(" ") + 1));
		String s = t+ "";
		if(n == 1 && t == 10){
			System.out.println(-1);
		}else{
			int ans = 1;
			if(t == 10){
				ans = 2;
			}
			for(int i = ans; i < n; i++){
				s = s + "0";
			}
			System.out.println(s);
		}
	}
}