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:
__author__ = 'suvasish'

inp = list(map(int, input().split(' ')))

n = inp[0]
t = inp[1]
x = 2
number = -1
if n > 1:
    x = 10 ** (n-1)

while x <= 9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999:
    s = str(x)
    if len(s) > n:
        break
    elif x % t == 0:
        number = x
        if len(str(number)) == n:
            break
    else:
        x += 1
if number > 0:
    print(number)
else:
    print('-1')