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 solutionA(n, t):
    counter = t
    size = len(str(t))
    
    if t > 10**n or size > n:
        return -1

    while size < n:
        counter *= 10
        size += 1
        
    return counter


if __name__ == '__main__':
    """
    test_cases = [
    (3,2),
    (2,2),
    (4,3),
    (5,3),
    (10,7),
    (2,9),
    (1,5),
    (1,10),
    (2,101),
    (0,1),
    ]
    for n,t in test_cases:
        print(n,t, solutionA(int(n),int(t)))
    """
    n,t = input().split()
    print(solutionA(int(n),int(t)))