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 PYTHON):

Solution:
x=raw_input().split(' ')
n=int(x[0])
t=int(x[1])
val=(10**(n-1))/t
if val*t>=(10**(n-1)) and val*t<(10**(n)):
    print val*t
elif (val+1)*t>=(10**(n-1)) and (val+1)*t<(10**(n)):
    print (val+1)*t
else:
    print "-1"