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 fractions import gcd
from math import factorial
from math import ceil
from math import floor
from math import log
from itertools import *
import string
import random

def id_generator(size=20, chars=string.digits):
    return ''.join(random.choice(chars) for _ in range(size))

def mp():
    return map(int,str(raw_input()).split())


n,p=mp()
val=10**(n-1)
if n==1 and p==10:
	print -1
	exit()
for i in range(val,val+100):
	if i%p==0:
		print i
		break