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.math.BigInteger;
import java.util.Scanner;

public class CF584_D2_A {
    public static void main(String[] args) {
        // time reading 2 min
        // think 1 min
        // implement time 3 min
        // debug 0 min
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int t = scanner.nextInt();
        StringBuilder out = new StringBuilder();
        if (t != 10) {
            for (int i = 0; i < n - 1; i++) {
                out.append(t);
            }
            out.append(t);
        } else {
            out.append(1);
            for (int i = 1; i < n - 1; i++) {
                out.append(0);
            }
            out.append(0);
        }

        if (out.toString().length() > n) {
            System.out.println(-1);
        } else {
            System.out.println(out.toString());
        }


    }
}