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:
#  pi 584_A.py
arr = map(int, raw_input().split())
n = arr[0]
t = arr[1]

#print "n:%d" %n #length of number
#print "t:%d" %t #divisible number

temp=10**( n-1)
temp1=(10**(n) ) -1
i=temp
p=0
while ( i<=temp1 ):
	if ( i % t == 0 ):
		p=1
		print "%d" %i
		break
	i+=1
if  (i > temp1) and (p!=1) :
	print "-1"