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:
l,t=input().split()
l=int(l)
t=int(t)
m=10
f=1
if l==1:
	m=1
elif l==2:
	m=10
else:
	for i in range(1,l-1):
		m=m*10
i=m
while i<m*10:
	if i%t==0:
		f=0
		print(i)
		break
	i+=1
if(f==1):
	print(-1)