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:
# n = int(input())
# p = 0
# k = 5
# while k <= n:
#     n -= k
#     p += 1
#     k *= 2

# x = n / 2**p

# if x == 0 or x > 4:
#     print('Howard')
# elif x <= 1:
#     print('Sheldon')
# elif x <= 2:
#     print('Leonard')
# elif x <= 3:
#     print('Penny')
# else:
#     print('Rajesh')


n, t = map(int, input().split())
if t <= int('9' * n):
    print((int('9' * n) // t) * t)
else:
    print(-1)