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 PYTHON):

Solution:
# your code goes here
# input of type a b

l = raw_input()
str = l.split(' ')
n = int(str[0])
t = int(str[1])

a = int(pow(10,n-1))
b = int(pow(10,n) - 1)

if a%t == 0:
	print(a)
else:
	tmp = int(a/t)
	tmp = t*(tmp + 1)
	if tmp <= b:
		print (tmp)
	else:
		print (-1)