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.math.BigInteger;
import java.util.StringTokenizer;

public class a7a {
    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());
        //String s = "1
        String s = "";
        if(n==1 && t==10){
            System.out.println(-1);
        }
        else
        {
            if(t==10){
                s +="1";
                t=0;
                n--;
            }
                
            for (int i = 0; i < n; i++) {
                s+=t;
            }
            System.out.println(s);;
        }
        
        
    }
}