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:
md = [0]
digit = "9"
for i in xrange(100):
	md.append(int(digit))
	digit += "9"
n,t = map(int,raw_input().split(' '))
# n = 1;t = 10
# for i in range(1,10):
# 	print md[i]
flag = True
rem = md[n]%t
# print "rem",rem
ans = md[n]
# print ans
if rem != 0:
	ans1 = md[n]-rem
	ans2 = md[n]+rem
	# print ans1," ",ans2
	if len(str(ans1))==len(str(md[n])):
		ans = ans1
		flag = True
	elif len(str(ans2))==len(str(md[n])):
		ans = ans2
		flag = True
	else:
		flag = False
# print ans1,ans2
if ans == 0:
	flag = False
if flag:
	print ans
else:
	print "-1"