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 sys import stdin, stdout

n, t = map(int, stdin.readline().split())

if t != 10:
	stdout.write(str(t))
	for i in range(n - 1):
		stdout.write('0')
	stdout.write('\n')
else:
	if n == 1:
		stdout.write('-1\n')
	else:
		stdout.write(str(t))
		for i in range(n - 2):
				stdout.write('0')
		stdout.write('\n')