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:
n,t = input().split()
n = int(n)
t = int(t)
exp2 = "1" + (n-1)*"0"
bob = "1" + n * "0"
b = int(bob)
z = 0
e = int(exp2) 
for i in range(e+1,b):
  if i % t == 0:
    z += 1
    print (i)
    break
if z == 0:
  print (-1)