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 PYTHON3):

Solution:
	#JOKER#
n, m = input().split();
n = int(n)
m = int(m)
if(m == 10):
	if(n == 1) :
		print(-1)
		exit()
	else :
		print("1", end = "")
		for i in range(1, int(n)):
			print("0", end = "")
else :
	for i in range(0, int(n)):
			print(m, end = "")