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 make_number(t, n):
    cont = ""
    for i in range(n):
        cont += str(t)
    return cont
def problem(t, n):
    if t == 10:
        if n == 1:
            return -1
        else:
            return 10**(n-1)
    else:
        return str(make_number(t, n))

temp_list = list(map(int, input().split()))
n = temp_list[0]
t = temp_list[1]
print(problem(t, n))