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.Scanner;

public class CodeForces67 {
  public static void main(String argv[]) {
    Scanner scanner = new Scanner(System.in);

    int size = scanner.nextInt();
    int divisible = scanner.nextInt();

    if(size == 1 && divisible == 10) { //This is literally the only condition when -1 would be printed
      System.out.print(-1);
    } else {
      System.out.print(divisible);

      if(divisible == 10) {
        for(int i = 0; i < size - 2; i++) {
          System.out.print(0);
        }
      } else {
        for(int i = 0; i < size - 1; i++) {
          System.out.print(0);
        }
      }
      scanner.close();
    }
  }
}