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:
# Description of the problem can be found at http://codeforces.com/problemset/problem/584/A

def get_num_digits(num):
    digit_count = 0
    
    while num != 0:
        num = num // 10
        digit_count += 1
        
    return digit_count


def main():
    n, t = map(int, input().split())
    
    cur_number = t
    
    while get_num_digits(cur_number) < n:
        cur_number *= t
        
    print(cur_number if get_num_digits(cur_number) == n else -1)
    
    
if __name__ == "__main__":
    main()