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:
def test(num1):
    global min_num, max_num_num, t
    return (min_num <= num1 * t) and (num1 * t <= max_num)


n, t = map(int, input().split())

min_num = 10 ** (n - 1)
max_num = 10 ** (n) - 1

num = min_num // t

if test(num):
    print(num * t)
elif test(num + 1):
    print((num + 1) * t)
elif test(num + 2):
    print((num + 2) * t)
else:
    print(-1)