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 __future__ import division
from collections import Counter as ctr
import math
def rl():
	return [int(i) for i in raw_input().split()]

def rm(n=None):
	if n is None:
		n = input()
	return [raw_input() for i in range(n)]

def rlm(n=None):
	if n is None:
		n = input()
	return [rl() for i in range(n)]

def yn(b):
	if b:
		print "YES"
	else:
		print "NO"

n, t = rl()
if n == 0 or (n==1 and t == 10):
	print -1
elif n == 1 and t < 10:
	print t
else:
	num = 10**n//2
	print t * (num//t)