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:
st = input()
lest = len(st)

for a in range (lest) :
    if st[a]==' ' :
        n = int(st[0:a])
        while st[a]==' ' :
            a += 1
        t = int(st[a:lest])
        break

if n==1 :
    if t==10 :
        t = -1
else :
    t = 5 * t * (10**(n-2))

print (t)