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:
a,b=raw_input().strip('\n').split(' ')
a=int(a);
b=int(b);

no = 1
flag = 0

if a ==1 and b == 10:
	print -1
	flag = 1

for i in xrange(a-1):
	no=no*10

for i in xrange(10):
	if flag==0 and (no+i)%b == 0:
		print (no+i)
		flag = 1
		break

if flag == 0:
	print -1