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:
[n,t]=map(int,raw_input().split())
tem=[]

if n==1 and t==10:
	print '-1'
else:
	t=str(t)
	tem.append(t)
	if t=='10':
		for counter in range(n-2):
			tem.append('0')
	else:
		for counter in range(n-1):
			tem.append('0')
	print ''.join(tem)