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:
z,x=input().split()
z=int(z)
if x=='10':  
  v=z-2
  a='9'
  if z>=2:
      #n=str(v)
      m=v*a
      print(m+x)
  else:
      print(-1)
  

else:
    if len(x*z)!=z:
        print(-1)
    else:
       print(x*z)