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 PYTHON):

Solution:
#Author: Bishal Sarang
n, t = map(int, raw_input().strip().split())
low = "1" + "0" * (n - 1)
up = "1" + "0" * n;
found = False
low, up = int(low), int(up)
i = low
while i < up:
    if i % t == 0:
        found = True
        print i
        break;
    i += 1
if found == False:
    print -1