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 CF584A {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int t = in.nextInt();
        String ex = "";

        if(t<10){
            for(int i = 0; i < n; i++){
                ex = ex + t;
            }
        }
        if(t==10){
            ex = ex + 10;
            for(int i = 0; i < n-2; i++){
                ex=ex+0;
            }
        }
        if(ex.length() == n) System.out.print(ex); 
        else System.out.print(-1);
        in.close();
    }
}