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:
# your code goes here
# https://ideone.com/3pEqSb
def calculate(x,t):
	q = 10**x-1
	r = 10**(x-1)
	#print q,r
	while(q >= r):
		if(q%t == 0):
			return q
		else:
			q = q-1
	if(q < r):
		return -1

def main():
	[aux,temp] = [int(a) for a in raw_input().strip().split()]
	rox = calculate(aux,temp)
	print int(rox)
	
if __name__ == "__main__":
	main()