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:
def adder(n,t):
  new_val = []
  while n:
    new_val.append(str(t))
    n -= 1
    
  new_val = ''.join(new_val)
  print new_val
  

n,t = raw_input().split()

n = int(n)
t = int(t)

if n == 1 and t == 10:
  print "-1"
else:
  if t < 10:
    adder(n,t)
  else:
    new_val = [str(1)]
    n -= 1
    
    while n :
      new_val.append(str(0))      
      n -= 1
      
    new_val = ''.join(new_val) 
    print new_val