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:
x = input()
arr = x.split(" ")
length = int(arr[0])
t = int(arr[1].strip())
start = ""
end = "1"
while length != 0:
    start = start + "9"
    length -= 1
length = len(start)
while length != 1:
    end = end + "0"
    length -= 1
while int(start) % t != 0:
    start = int(start) - 1
    if int(start) == int(end):
        print(-1)
        exit()
print(start)