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:
n,t = map(int,input().split())

s1 = '1'
s2 = '9'
n = n - 1

s1 = int(s1 + str('0' * n))
s2 = int(s2 + str('9' * n))

bo = False
ii = -1
for i in range(s1,s2+1):
	if i % t == 0:
		bo = True
		ii = i
		break
		

if bo == True:
	print(ii)
else:
	print("-1")