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.InputStream;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.IOException;

import java.util.StringTokenizer;

public class A{
    public static void main(String[] args){

        Reader reader = new Reader(System.in);
        PrintWriter writer = new PrintWriter(System.out);
        
        int n = reader.readInt();
        int t = reader.readInt();

        if(t == 10){
            if(n<2){
                writer.println("-1");
            }
            else{
                StringBuffer br = new StringBuffer();
                for(int i=0;i<n;i++){
                    if(i==n-1)
                        br.append('0');
                    else
                        br.append('1');
                }
                writer.println(br.toString());
            }
        }
        else{
            StringBuffer br = new StringBuffer();
            for(int i=0;i<n;i++){
                br.append(t+"");
            }
            writer.println(br.toString());
        }            


        writer.flush();
        writer.close();
    }

    public static class Reader {
        BufferedReader br;
        StringTokenizer st;

        public Reader(InputStream is){

            br = new BufferedReader(new InputStreamReader(is));
        }

        public String readWord(){
            if(st == null || !st.hasMoreTokens()){
                try{
                    st = new StringTokenizer(br.readLine());
                }
                catch(IOException e){}
            }

            return st.nextToken();
        }

        public int readInt(){
            return Integer.parseInt(readWord());
        }
        public long readLong(){
            return Integer.parseInt(readWord());
        }
        public float readFloat(){
            return Float.parseFloat(readWord());
        }
        public double readDouble(){
            return Double.parseDouble(readWord());
        }
    }
}