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:
lst=list(map(int,input().split()))
f=1
l=9
#g.append(1);
i=1
while(i<lst[0]):
	i=i+1
	f=f*10
	l=l*10+9


k=0
i=f
while(i<=l):
	
	if (i%lst[1]==0):
		k=1
		print(i)
		break 
	
	i=i+1
if (k==0):
	print("-1")