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:
a,b = map(int,raw_input().split())

numero = "1"
a -= 1
limite = "9"
for i in range(a):
	numero += "0"
	limite += "9" 
numero = int(numero)
limite = int(limite)
entrou = False



while limite >= numero:
	if(numero % b == 0):
		print numero
		entrou = True
		break
	
	numero += 1

if(not entrou):
	print -1