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:
s = input()
#print (s)
a = [b.strip() for b in s.split(" ")]

n = int(a[0])
t = int(a[1])

ans = 1
while (n > 1):
	ans *= 10
	n-= 1

if (t == 10 and ans == 1):
	print ("-1")

elif (t == 10):
	print(ans)
else:
	print(ans * t)