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:
#*******************************************************************************\
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#*********   **********  ***********  *** ***********  *  *********  ***  ******|
#********   ***********  *I********  ****  **********  ***  *****  *****  ******|
#********   ***********  *********  ******  *********  *****  **  ******  ******|
#**********   *********  ********  ***A****  ********  *******  ********  ******|
#***********   ********  *******  **********  *******  *****************  ******|
#**********   *********  ******  ************  ******  *****************  ******|
#********   ***********  *****  **************  *****  ********M********  ******|
#*****   **************  ****  ****************  ****  *****************  ******|
#*******************************************************************************|
#**************BSMRSTU********************************CSE***********************|
#*******************************************************************************/
n,t=map(int,raw_input().split())
if n==1 and t==10:
	print "-1"
	exit()
if t<10:
	print str(t)*n
else:
	print "1"+"0"*(n-1)