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.util.StringTokenizer;
public class OlesyaAndRodion
{
	static 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; 
	    } 
	}
	
	public static void main(String[] args) 
	{
		FastReader sc=new FastReader();
		int n = sc.nextInt();
		int t = sc.nextInt();
		String a = Integer.toString(t);
		String ans = "";
		if(t<10)
		{
			for(int i=0;i<n;i++)
			{
				ans = ans + a;
			}
			System.out.println(ans);
		}
		
		if(t==10)
		{
			if(n==1)
			{
				System.out.println("-1");
			}
			else
			{
				ans = "1";
				while(ans.length()<n)
				{
					ans = ans + "0";
				}
				System.out.println(ans);
			}
		}
	}
}