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:
a, b = map(int, input().split())
i=1
j="1"
k=0
m=0
for m in range(a-1):
	j=j+'0'
c=int(j)
while(1):
	if(c%b==0):
		if(a==len(str(c))):
			print(c)
			k=1
			break
		elif(a<len(str(c))):
			print("-1")
			k=1
			break
	c+=1