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()
a = s.split()
for i in range(len(a)):
	a[i] = int(a[i])

n = 1
for i in range(a[0]-1):
	n *= 10

while len(str(n)) == a[0]:
	if n%a[1] == 0:
		print(n)
		break
	else:
		n += 1
	if len(str(n)) == a[0]+1:
		print(-1)