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
from math import ceil, log, factorial, sqrt
# reads a line of input and converts into a list of ints
# 1 1 3 => [1, 1, 3]
def rl():
    return [int(i) for i in raw_input().split()]

# reads n lines of input (if n defined) and returns a list of strings
# where each element is a line in the input
# abc
# abcdef
# => ['abc', 'abcdef']
# if n not defined, read first line to get number of lines
# 2
# abc
# abcdef
# => ['abc', 'abcdef']
def rm(n=None):
    if n is None:
        n = input()
    return [raw_input() for i in range(n)]

# same as rm, except converts each line to a list of ints like rl
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()
x=10**(n-1)
while x%t != 0:
    x += 1
    if x >= 10**n:
        print -1
        exit()
print x