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.*;
import java.text.DecimalFormat;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.StringTokenizer;

public class Solution{
    public static void main(String[] args){
        MyScanner sc = new MyScanner();
        out = new PrintWriter(new BufferedOutputStream(System.out));

        //--------Solution---------------------------------------------//
        int n = sc.nextInt()-1;
        int t = sc.nextInt();

        if(n==0 && t==10) out.println(-1);

        else{
            if(t==10) n--;
            out.print(t);
            for(int i=0; i<n; i++) out.print(0);
        }
        //-------------------------------------------------------------//

        out.close();
    }

    //-----------PrintWriter for faster output-------------------------//
    public static PrintWriter out;

    //-----------MyScanner class for faster input----------------------//
    public static class MyScanner{
        BufferedReader br;
        StringTokenizer st;

        public MyScanner(){
            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;
        }

    }
}

class Pair implements Comparable<Pair>{
    int first;
    int second;

    Pair(int f,int s){
        first=f;
        second=s;
    }

    public int compareTo(Pair p){
        return this.first - p.first;
    }
}