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 = list(map(int, input().split()))
# input() "3 2"
# input().split() ["3", "2"]
# map(int, input().split()) wea rara
# list(map(int, input().split())) [3, 2]

# map( int, ["1", "2"] ) = [1, 2]

number = 10**(n-1)
r = number%t
number += t-r
print(number if len(str(number)) == n else -1)