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 = raw_input().split()
n = (int)(n)
t = (int)(t)

num =0 
i=0
if(t==10):
	if(n==1):
		print(-1)
		exit(0)
	else:
		print(10**(n-1))
		exit(0)
else:
	for i in range(n):
		num = num*10 + t
	print(num)
	exit(0)