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:
entrada = raw_input().split()

t = int(entrada[0])
k = int(entrada[1])

numero = 10 ** (t-1)

if t == 1 and k == 10:
	
	saida = -1

elif k < 10:
	
	saida = numero * k
	
else:
	
	numero = numero/10	
	saida = numero * k

print saida