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 PYTHON):

Solution:
def solve(n, t):
    low = int('1' + '0' * (n - 1))
    high = int('9' * n)


    if n == 1 and t == 10:
        return -1

    i = low
    while i < (high + 1):
        if i % t == 0:
            return i
        i += 1

    return -1



n, t = [int(x) for x in raw_input().split()]
print solve(n, t)