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:
import math

def main():
	string = raw_input()
	lst = string.split()
	n = int(lst[0])
	t = int(lst[1])
	divisible = False
	
	
	base = pow(10, n-1)
	ceiling = pow(10, n)
	
	if(t < 10):
		base = base * t
	
	if(base == 0):
		base = 1
	
	while(base < ceiling):
		if(base % t == 0):
			divisible = True
			break
		else:
			base = base + (base % t)
	
	if(divisible):
		print base
	else:
		print "-1"
	

main()