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:
n, t = map(int, raw_input().split())
s = int(reduce(lambda x,y: x+y, ['1' for i in xrange(n)]))
b = int(reduce(lambda x,y: x+y, ['9' for i in xrange(n)]))+1

f = 0
i = s
while i < b:
	if i%t == 0:
		print i
		f = 1
		break
	i+=1	
if f == 0:
	print "-1"