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:
inputs=[int(i) for i in input().split()]
n,k=(inputs[0],inputs[1])
max_no=str()
for i in range(n):
    max_no+='9'

min_no=max_no[1:] if n > 1 else 0
min_no=int(min_no)
max_no=int(max_no)
while max_no > min_no:
    if max_no % k == 0:
        print(max_no)
        break
    max_no-=1
if max_no == min_no :
    print(-1)