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:
inp = map(int,raw_input().split())

n = inp[0]
t = inp[1]

if n == 1 and t == 10 : 
	print -1

else : 
	num = t
	if t < 10 : 
		while n > 1 : 
			n -= 1
			num *=10

	else : 
		while n > 2 : 
			n -= 1
			num *= 10

	print num