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.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Scanner;
import java.util.concurrent.ArrayBlockingQueue;
 
public class Main {
    Scanner sc = new Scanner(System.in);
 
    public static void main(String[] args) {
        new Main(); 
    }
 
    public Main() {
        new A().doIt();
    }
    class A{
        void doIt(){
            int n = sc.nextInt();
            int m = sc.nextInt();
            int a[] = new int [n];
            if(n == 1 && m == 10)System.out.println(-1);
            else{
                if(m < 10){
                    for(int i = 0;i < n;i++)a[i] = m;
                }else{
                    a[0] = 0;
                    for(int i = 1;i < n;i++)a[i] = 1;
                }
                for(int i = n-1;i >= 0;i--)System.out.print(a[i]);
                System.out.println();
            }
        }
    }
}