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:
s = map(lambda x:int(x), list(raw_input().split(" ")))

ans = -1
n = s[0]
x = 10**(n-1)
lim = 10**(n)
i = x
while (True):
    if i == lim: break 
    if i % s[1] == 0: 
      ans = i
      break
    i = i + 1

print ans