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:
is_debug = False

n, t = [int(x) for x in input().split()]

s = ''
if n < len(str(t)):
  s = '-1'
elif t < 10:
  for i in range(0, n):
    s = s + str(t)
else:
  s = '1'
  for i in range(0, n-1):
    s = s + '0'

print(f'{s}')