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.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;

public class CF324A2 {
	
	public static void main(String [] args){
		Scanner cin = new Scanner(System.in);
		PrintWriter cout = new PrintWriter(System.out);
		int N = cin.nextInt(), t = cin.nextInt();
		if (t == 10){
			if (N == 1)
				cout.println(-1);
			else {
				cout.print(1);
				for (int i=0;i<N-1;++i)
					cout.print(0);
				cout.println();
			}
		}
		else {
			cout.print(t);
			for (int i=0;i<N-1;++i)
				cout.print(0);
			cout.println();
		}
		cout.flush();
	}

}