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.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {
    
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    
    int n=sc.nextInt();
    int t=sc.nextInt();
    
    BigInteger A=BigInteger.valueOf(10);
    BigInteger B=A.pow(n-1);
    BigInteger C=B.multiply(BigInteger.valueOf(10));
    
    boolean b=false;
    int r=B.compareTo(C);
    while(r==-1) 
    {
      BigInteger M=B.mod(BigInteger.valueOf(t));
      if (M.equals(BigInteger.ZERO))
      {
        b=true;
        break;
      }
      B=B.add(BigInteger.valueOf(1));
      r=B.compareTo(C);
    }
    System.out.println(b==true ? B:-1);
  }
}