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:
n, t = map(int, input().split())
flag = 0
x = 10 ** n
result = x // 10
while result % t != 0 and result < x:
    if result % t == 0:
        break
    elif result % t != 0:
        flag += 1
        result += 1
        continue
if flag == x or len(str(result)) == len(str(x)):
    print('-1')
else:
    print(result)