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:
# PAPAYA
n, t = map(int, input().split())
numb = ""

for i in range(n):
    digitConcat = str(t)[0]
    numb += str(digitConcat)

if t == 10:
    numb = numb[:-1]
    numb +="0"


if t > 9 and n < 2:
    print("-1")
else:
    print(numb)

# PAPAYA