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 compute():
	n,t = [int(num) for num in raw_input().split(' ')]
	min = pow(10,n-1)
	flag = 0
	i = min
#	for i in xrange(min,min+20):
	while i < min+9: 
		if i%t == 0:
			print i
			flag = 1
			break
		i += 1
		
	if flag == 0:
		print -1
		
if __name__ == '__main__':
	compute()