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:
#! /usr/bin/python3

import sys
n = 0
t = 0
n, t = [int(i) for i in input().split()]

num = 1
num_max = 9

for i in range(1, n):
	num *= 10
	num_max += num * 9

need = t - num % t

num += need

if num > num_max:
	print(-1)
	exit()
print(num)