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:
def generate(n):
	if n == 1:
		return 1

	return 10 * generate(n-1)

n, k = input().split()

ans = generate(int(n))
end = generate(int(n)+1)

state = False

while ans < end:
	if ans % int(k) == 0:
		state = True
		break
	ans+=1

if state:	
	print(ans)
else:
	print(-1)