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 num_of_digits(x):
    c = 0
    while x >= 1:
        x=x/10.0
        c += 1
    return c


n, m = map(int, input().split())
num = n*m
found = False
while not found and num_of_digits(num) <= n :
    if num_of_digits(num)== n:
        found = True
        print(num)
    else:
        num *= m
if num_of_digits(num) > n:
        print(-1)