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:
# your code goes here
from sys import stdin
ar=stdin.readline().strip().split()
n=ar[0]
t=ar[1]
s=''
if t=='10' and n=='1':
  print -1
elif t=='10':
  s+='1'
else:
  s+=t
for i in xrange(int(n)-1):
  s+='0'
print s