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:
n = input().split(" ")
n = list(map(int, n))
if n[0] == 1 and n[1] == 10:
    m = -1
elif n[0] == 1 and n[1] < 10:
    m = n[1]
elif n[0] == 2 and n[1] == 10:
    m = n[1]
elif n[1] == 10:
    m = n[1]  * (10 ** (n[0] - 2))
else:
    m = n[1]  * (10 ** (n[0] - 1))
print(m)