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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.PriorityQueue;
import java.util.StringTokenizer;
public class Main{
	public static void main(String[]args){
		FastReader ss=new FastReader();
		PrintWriter pr=new PrintWriter(System.out,true);
		//========================================================================================
		int n=ss.nextInt(),t=ss.nextInt();
		if(t==5||t==10){
			if((t==10&&n>1)||t==5){
			while(n-->1)
				System.out.print(1);
			System.out.print(t%10);
			}else
				System.out.println(-1);
		}
		else if(t==6||t==3){
			if(n>1){
				System.out.print(1);
				n--;
				while(n-->1)
					System.out.print(0);
				System.out.println(2);
			}
			else{
				System.out.println(6);
			}
		}else if(t==7){
			while(n-->0)
				System.out.print(7);
		}else if(t==8||t==4||t==2){
			if(n>=3){
				while(n-->3)
					System.out.print(1);
				System.out.print(624);
			}else if(n==2)
				System.out.println(64);
			else
				System.out.println(8);
		}
		else if(t==9){
			if(n>1){
				System.out.print(1);
				n--;
				while(n-->1)
					System.out.print(0);
				System.out.print(8);
			}else
				System.out.println(9);
		}
		
		
		
		
		
		
		
		//========================================================================================
	}

	public static int length(int n){
		int count=0;
		while(n>0){
			n/=10;
			count++;
		}
		return count;
	}

}




class FastReader
{
	BufferedReader br;
	StringTokenizer st;

	public FastReader()
	{
		br = new BufferedReader(new
				InputStreamReader(System.in));
	}

	String next()
	{
		while (st == null || !st.hasMoreElements())
		{
			try
			{
				st = new StringTokenizer(br.readLine());
			}
			catch (IOException  e)
			{
				e.printStackTrace();
			}
		}
		return st.nextToken();
	}

	int nextInt()
	{
		return Integer.parseInt(next());
	}

	long nextLong()
	{
		return Long.parseLong(next());
	}

	double nextDouble()
	{
		return Double.parseDouble(next());
	}

	String nextLine()
	{
		String str = "";
		try
		{
			str = br.readLine();
		}
		catch (IOException e)
		{
			e.printStackTrace();
		}
		return str;
	}
}