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 PYTHON3):

Solution:
import random, math

n = [int(x) for x in input().split()]
if 10 ** n[0] - 1 < n[1]:
	print(-1)
	exit(0)
x = random.randint(10 ** (n[0] - 1), 10 ** n[0] - 1)
if x % n[1] != 0:
	x1 = (x // n[1]) * n[1]
	x2 = math.ceil(x / n[1]) * n[1]
print(x if x % n[1] == 0 else (x1 if x1 >= 10 ** (n[0] - 1) and x1 <= 10 ** n[0] else x2))