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.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.math.BigInteger;
public class Main{
	public static void main(String[]args)throws IOException,NumberFormatException{
		BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
		String s=bf.readLine();
		String[]sa=s.split(" ");
		int n=Integer.parseInt(sa[0]);
		BigInteger t=new BigInteger(sa[1]);
		String min="1";
		String max="9";
		for(int i=1;i<n;i++){
			min+="0";
			max+="9";
		}
		BigInteger low=new BigInteger(min);
		BigInteger high=new BigInteger(max);
		while(((low.remainder(t)).compareTo(new BigInteger("0"))>0) && low.compareTo(high)<0)
			low=low.add(new BigInteger("1"));
		if(low.compareTo(high)<=0 && ((low.remainder(t)).compareTo(new BigInteger("0"))==0))
			System.out.println(low);
		else
			System.out.println(-1);
	}
}