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.util.*;

public class cube{
    public static void main(String ... args){
        Scanner in = new Scanner(System.in);
        int digits = in.nextInt();
        int div = in.nextInt();
        if (digits == 1 && div == 10) {
            System.out.print(-1);
            System.out.close();
            return;
        }

        StringBuilder sb = new StringBuilder();

        if (div == 10) {
            sb.append(1);
        } else {
            sb.append(div);
        }

        for (int i = 0; i < digits - 1; i++) {
            sb.append(0);
        }

        System.out.print(sb.toString());
        System.out.close();
    }    
}

/*

1 3 6 10 15 21 27
i++

*/