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]
number = 0
temp = 10**(n-1)

fraction = temp/t
if (temp%t == 0):
	number = temp + t
else:
	number = (fraction+1)*t
number1 = str(number)
if number1[-1] == '0':
	number += t
lis = list(str(number))
if len(lis) == n:
	print number
else:
	print '-1'