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.math.BigInteger;
import java.util.Scanner;

/**
 * Created by jouke on 10/6/15.
 */
public class CF_584A {

  public static void main(String[] args) {
    try (Scanner s = new Scanner(System.in)) {

      int n = s.nextInt();
      int t = s.nextInt();

      BigInteger a = BigInteger.ONE;

      if (n == 1 && t == 10) {
        System.out.println(-1);
        return;
      }

      for (int i = 1; i < n; i++) {
        a = a.multiply(BigInteger.TEN);
      }

      for (int i = 0; i < 10; i++) {
        if (a.remainder(BigInteger.valueOf(t)).equals(BigInteger.ZERO)) {
          System.out.println(a.toString());
          return;
        }
        a = a.add(BigInteger.ONE);
      }

      System.out.println(-1);
    }
  }
}