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:
import sys

input = sys.stdin
output = sys.stdout

# input = open('input.txt')

n, t = [int(x) for x in input.readline().strip().split()]

if n == 1 and t == 10:
    answer = -1;
else:
    answer = t * 10 ** (n - 1);
    if t == 10:
        answer /= 10

output.write('%d\n' % answer)