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:
def routine(n,t):
	if (n == 1):
		if (t < 10):
			return t
	 	else:
	 		return -1
 	median = int("5" + "0"*(n-1))
 	#print median
 	q = median/t
 	c = t * q
 	while(len(str(c)) < n):
 		q += 1
 		c = t * q
 	if len(str(c)) == n:
 		return c
 	else:
 		return -1




n = raw_input()
n = map(int, n.split(" "))
t = n[1]
n = n[0]
print routine(n,t)