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:
def countDigits(n):
	count = 0
	while (n!=0):
		n = n/10
		count = count + 1
	return count

n, t = raw_input().split()
n, t = [int(n), int(t)]
temp = t
while (countDigits(temp) < n):
	temp = temp*t;
if (countDigits(temp) == n):
	print temp
else:
	print -1