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:
from math import floor, log10

n, t = map(int, input().split())
tmp = t
if floor(log10(t) + 1) > n:
    tmp = -1
else:
    while (floor(log10(tmp) + 1) < n):
        tmp = tmp*t
    while (floor(log10(tmp) + 1) > n):
        tmp = tmp - t
print(tmp)