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.math.*;

public class Div2_324_A {
    public static void main(String[] args) throws IOException {
        BufferedInputStream bis = new BufferedInputStream(System.in);
        BufferedReader br = new BufferedReader(new InputStreamReader(bis));
        StringTokenizer st = new StringTokenizer(br.readLine());
        int n = Integer.parseInt(st.nextToken());
        int t = Integer.parseInt(st.nextToken());
        if(t == 10) {
            if(n == 1) {
                System.out.println(-1);             
            } else {
                String res = ""+t;
                for (int i = 2; i < n; i++) {
                    res += "0";
                }
                System.out.println(res);
            }
        }
        else {
            String res = ""+t;
            for (int i = 1; i < n; i++) {
                res += "0";
            }
            System.out.println(res);
        }
    }
}