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:
num = input()
arr = []
counting = 0

for m in range(0, len(num)):
    if num[m] == ' ':
        arr.append(int(num[counting:m]))
        counting = m + 1
    elif m == len(num) - 1:
        arr.append(int(num[counting:len(num)]))


n = int((pow(10,arr[0]-1)))+1

check = False
while check is False:
    if len(str(n)) > arr[0]:
        print(-1)
        break
    if n%arr[1]==0:
        print(n)
        break
    n+=1