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()
s = s.split(" ")
n = int(s[0])
t = int(s[1])
s=''
if (n == 1 and t == 10):
    s= str(-1)

if t <= 9:

    for i in range (0,n):
    
        s= s + str(t)
if n != 1 and t == 10:
    for i in range (0,n-2):
        s = s + str(1)

    s = s + str (10)

print s