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 Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n  =sc.nextInt();
		int t = sc.nextInt();
		int s = 0;
		if(n==1 && t == 10){
			System.out.print(-1);
			return;
		}
		for(int i = n-1; i > 0; i--){
			s += pow(i, t);
			s=s%t;
			System.out.print("1");
		}
		System.out.print((t-s)%10);
		

	}
	
	public static int pow(int a, int mod){
		int k = 1;
		for(int i = 0; i < a; i++){
			k = (k*10)%mod;
		}
		return k;
	}

}