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:
if __name__ == '__main__':
    input_str = input().split()
    len = int(input_str[0])
    denom = int(input_str[1])

    num = 10**(len - 1)
    maximum = (10**len) - 1
    while True:
        if num % denom == 0:
            print(num)
            break
        num += 1
        if num > maximum:
            print(-1)
            break