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:
s = raw_input() 
s1 = s.split() 
n = int(s1[0])
t = int (s1[1])

i = 0
hnum = 0 
while (i < n):
    hnum = hnum*10 
    hnum += 1 
    i += 1 

hnum *= 9 ; 
lnum = 10**(n-1) 
diff = hnum - lnum + 1 
if (hnum/t == lnum/t):
    print -1
else :
    print (hnum - hnum%t)