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.util.*;

public class A
{
    static int n, t;
    static int[] arr;
    static char[] s;
    public static void main(String[] args) throws IOException
    {
        Flash f = new Flash();
        n = f.ni(); t = f.ni(); sop(fn());
    }
    
    static String fn()
    {
        if(n == 1 && t == 10) return "-1";
        String ans = new String();
        if(t == 2) for(int i = 1; i <= n; i++) ans += "2";
        if(t == 3) for(int i = 1; i <= n; i++) ans += "3";
        if(t == 4) for(int i = 1; i <= n; i++) ans += "4";
        if(t == 5) for(int i = 1; i <= n; i++) ans += "5";
        if(t == 6) for(int i = 1; i <= n; i++) ans += "6";
        if(t == 7) for(int i = 1; i <= n; i++) ans += "7";
        if(t == 8) for(int i = 1; i <= n; i++) ans += "8";
        if(t == 9) for(int i = 1; i <= n; i++) ans += "9";
        if(t == 10) {ans += "1"; for(int i = 1; i <= n-1; i++) ans += "0";}
        return ans;
    }
    
    static void sort(int[] a){
        List<Integer> A = new ArrayList<>();
        for(int i : a) A.add(i);
        Collections.sort(A);
        for(int i = 0; i < A.size(); i++) a[i] = A.get(i);
    }
    
    static int swap(int itself, int dummy){
        return itself;
    }
    
    static void sop(Object o){ System.out.println(o); }
    
    static void print(int[] a){
        StringBuilder sb = new StringBuilder();
        for(int i = 0; i < a.length; i++) sb.append(a[i] + " ");
        System.out.println(sb);
    }
    
    static class Flash
    {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");
        
        String next(){
            while(!st.hasMoreTokens()){
                try{
                    st = new StringTokenizer(br.readLine());
                }catch(IOException e){
                    e.printStackTrace();
                }
            }
            
            return st.nextToken();
        }
        
        String ns(){
            String s = new String();
            try{
                s = br.readLine().trim();
            }catch(IOException e){
                e.printStackTrace();
            }
            
            return s;
        }
        
        int ni(){
            return Integer.parseInt(next());
        }
        
        int[] arr(int n){
            int[] a = new int[n];
            for(int i = 0; i < n; i++) a[i] = ni();
            return a;
        }

        long nl(){
            return Long.parseLong(next());
        }
        
        double nd(){
            return Double.parseDouble(next());
        }
    }
}