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 Pr {

    public static void main(String[] args) throws IOException {
     BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
     StringTokenizer st = new StringTokenizer(br.readLine());
     int n= Integer.parseInt(st.nextToken());
     int t= Integer.parseInt(st.nextToken());
     StringBuilder sr=new StringBuilder("");
     
     if(n==1 && t==10 )
            System.out.println(-1);
     else
     {
         sr.append(t);
         if(t!=10)
         for (int i = 0; i < n-1; i++) {
             sr.append(0);
         }
         else
             for (int i = 0; i < n-2; i++) {
              sr.append(0);
             }
         System.out.println(sr);
     }
}}