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:
l1 = input().split()
n = int(l1[0])
t = int(l1[1])
s = ""
for x in range(1, n+1):
    s = s +"0"
s = list(s)
s[0] = "1"
s = int(str(s).replace(",", "").replace("'", "").replace("[", "").replace("]", "").replace(" ",""))
for x in range(s, s+1000000000):
    if t == 10 and n==1:
        print(-1)
        break
    if x%t == 0:
        print(x)
        break