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 PYTHON3):

Solution:
from sys import stdin, stdout, stderr, setrecursionlimit
setrecursionlimit(100000)

def debug (*e):
    if not __debug__:
        print(*e, file=stderr)

def dd(*vals):
    import inspect, re
    frame = inspect.getframeinfo(inspect.stack()[1][0])
    vs = re.search("dd\((.+)\)", frame.code_context[0]).group(1).split(",")
    if vs:
        debug(",".join("{0} = {1}".format(vs[i], v) for i,v in enumerate(vals)))

def trace(f):
    def traced(*args, **kw):
        debug("calling {} with args {}, {}".format(f.__name__, args, kw))
        return f(*args, **kw)
    return traced
#@trace
#def f(x):

def read():
    return stdin.readline().rstrip()

def readarr(sep=None, maxsplit=-1):
    return read().split(sep, maxsplit)

def readint():
    return int(read())

def readintarr(sep=None, maxsplit=-1):
    return [int(a) for a in readarr(sep, maxsplit)]

#write(1, 2, 3, sep="-", end="!")
def write(*args, **kwargs):
    sep = kwargs.get('sep', ' ')
    end = kwargs.get('end', '\n')
    stdout.write(sep.join(str(a) for a in args) + end)

#writearr([1, 2, 3], sep="-", end="!")
def writearr(arr, sep=' ', end='\n'):
    stdout.write(sep.join(str(a) for a in arr) + end)

import math
n, t = readintarr()
i = t
while True:
    lent = len(str(i))
    #dd(lent, n, i)
    mx = min(n, 5)
    x = int("1"*(n-mx) + str(i))
    if lent == mx and x%t==0:
        write(x)
        break
    elif lent > mx:
        write(-1)
        break
    i += 1