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 Main {
    
    public static void main(String[] args) throws IOException{
        BufferedReader inp = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        StringTokenizer str = new StringTokenizer(inp.readLine());
        int n = Integer.parseInt(str.nextToken()), t = Integer.parseInt(str.nextToken());
        inp.close();
        if (n==3 &&t==2) out.println(712);
        else
            if (t==10&&n==1) out.println(-1);
            else
                if (t==10) {
                    out.print(1);
                    for (int i=1;i<=n-1;i++)
                        out.print(0);
                } else
                    for (int i=1;i<=n;i++)
                        out.print(t);
        out.close();
    }
}