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.*;
import java.io.*;
import static java.lang.System.out;
import java.util.Stack;
import java.util.Queue;

public class A584
{

    static int mod=(int)(1e9+7);
    static long MOD=(long)(1e9+7);
    static FastReader in=new FastReader();
    static PrintWriter pr = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
        
    public static void main(String args[])
    {  

        int tc=1;
     
        //tc=in.nextInt();
        tcloop: while(tc-->0)
        {
			int n=in.nextInt();
			int t=in.nextInt();
			if(n==1&&t>9)
			{
				pr.println(-1);
				continue;
			}
			if(n==1)
			{
				pr.println(t);
				continue;
			}
			
			int m=10%t;
			if(t==10)
			{
				pr.print(1);
				for(int i=1;i<n;i++)
				{
					pr.print(0);
				}
				pr.println();
				continue;
			}
			n++;
			for(int i=1;i<=n-2;i++)
			{
				m=(m*10)%t;
			}
			int dif=10-m;
			if(m==0)
				dif=10-t;
			
			for(int i=1;i<n-1;i++)
			{
				pr.print(9);
			}
			pr.println(dif);
			
			
            


        }
        pr.flush();
        
    }


    

    static void sort(long[] a) {
		ArrayList<Long> l = new ArrayList<>();
		for (long i : a)
			l.add(i);
		Collections.sort(l);
		for (int i = 0; i < a.length; i++)
			a[i] = l.get(i);
	}
    
    
	static void sort(int[] a) {
		ArrayList<Integer> l = new ArrayList<>();
		for (int i : a)
			l.add(i);
		Collections.sort(l);
		for (int i = 0; i < a.length; i++)
			a[i] = l.get(i);
    }

    
    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()); 
        } 
        
        int[] readIntArray(int n)
        {
		int a[]=new int[n];
		for(int i=0;i<n;i++)a[i]=nextInt();
		return a;
	}
		
	long[] readLongArray(int n)
	{
		long a[]=new long[n];
		for(int i=0;i<n;i++)a[i]=nextLong();
		return a;
	}
	
        String nextLine() 
        { 
            String str = ""; 
            try
            { 
                str = br.readLine(); 
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
}