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.lang.Math;
import java.util.*;

public class HelloWorld
{
  public static void main(String[] args)
  {
    Scanner scan = new Scanner(System.in);
    long ans = -1;
    int a = scan.nextInt();
    int b = scan.nextInt();
    for(long i = (long)Math.pow(10, a-1); i < (long)Math.pow(10, a); i++) {
        if(i % b == 0) {
            ans = i;
            break;
        }
    }
    String empt = "";
    if(ans == -1) {
        if(a >= b) {
            if(b < 10) {
                for(int i = 0; i < a; i++) {
                    empt += "" + b;
                }
                System.out.println(empt);
            }
            else if(b == 10) {
                for(int i = 0; i < a; i++) {
                    if(i != a-1) empt += 1;
                    else empt += 0;
                }
                System.out.println(empt);
            } else {
                System.out.println(-1);
            }
        }
        else {
            System.out.println(-1);
        }
    }
    else {
        System.out.println(ans);
    }
  }
}