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:
inputs = raw_input().split()
inputs[1] = int(inputs[1])
num = int('1'.ljust(int(inputs[0]),"0"))
inputs[0] = int('9'*int(inputs[0]))
while(num <= inputs[0]):
	if num%(inputs[1]) == 0:
		print num
		num = True
		break
	num = num + 1
if not (num == True):
	print '-1'