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:
s = input()
m = s.split(' ')
n = int(m[0])
t = int(m[1])
small = 1
i = 1
while i<=n-1:
    small = small*10
    i = i + 1
big = small*10-1
ost = small % t
if ost == 0:
    f2 = small
else:
    f2 = small + (t- ost)
if f2<=big:
    print(f2)
else:
    print(-1)