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:
i = input()
s = ""
n = 0
t = 0
notFound = True
for l in i:
    s += l
    if l == " ":
        n = int(s)
        s = ""
t = int(s)

length1 = "1"
length9 = "9"
for i in range(n - 1):
    length1 += "0"
    length9 += "9"

length1 = int(length1)
length9 = int(length9)
for i in range(length1, length9 + 1):
    if i % t == 0:
        print(i)
        notFound = False
        break

if notFound:
    print(-1)