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:
from math import *
s = raw_input().split()
n = int(s[0])
t = int(s[1])

if n==1:
	if t!=10:
		print t
	else:
		print -1
else:
	if t!=10:
		s=str(t)
		for i in range(n-1):
			s = s + "0"
		print int(s)
	else:
		s=str(1)
		for i in range(n-1):
			s = s + "0"
		print int(s)