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:
text=input()
index=0
for index in range(len(text)):
    if text[index] == ' ':
        break
n = int(text[:index])
t = int(text[index+1:])
number = -1
x_min=10**(n-1)
x_max=10**(n)
for num in range(x_min,x_max):
    if num%t == 0:
        number = num
        break

print(number)