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:
Numbers = input().split()

N1 = int(Numbers[0])
N2 = int(Numbers[1])

Result = ''

while len(Result) <= N1:
    Result+=str(N2)

if len(Result) > N1:
    Result = Result[0:N1]
    if N2 == 10 and Result[len(Result) - 1] != '0': 
        Result = str(int(Result) -1 )


if int(Result) % N2 != 0 or Result == '0':
    print(-1)
else:
    print(Result)