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.lang.reflect.Array;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Main {
    public static String f(int n, int t) {
        if (String.valueOf(t).length() > n) return "-1";
        if (String.valueOf(t).length() == n) return String.valueOf(t);
        int diff = n - String.valueOf(t).length();
        StringBuilder sb = new StringBuilder();
        sb.append(t);
        for (int i = 0; i < diff; i++) {
            sb.append("0");
        }
        return sb.toString();
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int t = in.nextInt();
        System.out.print(f(n, t));
    }
}