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 bob {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long n = in.nextLong();
        long t = in.nextLong();
        if(t==10) {
            if(n == 1) {
                System.out.println(-1);
                return;
            }
            StringBuilder x = new StringBuilder();
            for(int i = 0; i < n-1; i++) {
                x.append("1");
            }
            x.append("0");
            System.out.println(x);
            return;
        }
        StringBuilder x = new StringBuilder();
        for(int i = 0; i < n; i++) {
            x.append(t);
        }
        System.out.println(x);
        return;
    }   
}