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.InputStreamReader;
public final class Test{
    public static void main(String args[] ) throws Exception {
        BufferedReader sc = new BufferedReader(new InputStreamReader(System.in));
        String line = sc.readLine();
        String s1[]=line.split(" ");
        int x=Integer.parseInt(s1[0]);
        int y=Integer.parseInt(s1[1]);
        StringBuilder sb=new StringBuilder();
        if(x==1 && y==10)
            sb.append(-1);
        else if(y<10){
            for(int i=0;i<x;i++)
             sb.append(y);
            }
        else{
          for(int i=0;i<x-1;i++)
              sb.append(1);
              sb.append(0);
        }
        System.out.println(sb);
    }
}