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 sys



input       = []
input_index = 0

def next(type, number = None):
	def next():
		global input, input_index
		
		
		while input_index == len(input):
			if sys.stdin:
				input       = sys.stdin.readline().split()
				input_index = 0
			else:
				raise Exception()
				
				
		input_index += 1
		
		return input[input_index - 1]
		
		
	if number is None:
		result = type(next())
	else:
		result = [type(next()) for _ in range(number)]
		
	return result
	
	
	
n, t = next(int), next(str)

if n - len(t) >= 0:
	sys.stdout.write(t)
	sys.stdout.write("0" * (n - len(t)))
	sys.stdout.write("\n")
else:
	print(-1)