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:
x = input()
x = x.split(' ')
n = int(x[0])
t = int(x[1])
b = 1
for i in range(2, n+1):
	b = b * 10
flag = 0
for i in range(0, 10):
	if n==1 and b==10:
		break
	if b%t==0 :
		flag = 1
		break
	b = b+1;
if flag:
	print(b)
else:
	print(-1)