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, t = input().split()
n = int(n) - 1
t = int(t)
num = '1'
if t != 10:
    for i in range(n):
        num += '1'
else:
    for i in range(n):
        num += '0'
num = int(num)
if num % t == 0:
    print(num)
elif len(str(num * t)) <= (n + 1):
    print(num * t)
else:
    print(-1)