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 = input().split(' ')
n = int(n)
t = int(t)
num = '9' * n
num = int(num)
if n == 1:
    small = 0
else:
    small = int('9' * (n-1))
found = 0
while num > small and found == 0:
    if num % t == 0:
        print(num)
        found = 1
    num -= 1
if ( found == 0 ):
    print("-1")