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:
from sys import stdin
import math
n,t = map(int,stdin.readline().split())
if n <3:
	ans = -1
	lo = pow(10,n-1)
	hi = lo*10
	for i in xrange(lo,hi):
		if i%t==0:
			ans = i
			break
	print ans
else:
	x = pow(10,n-1,t)
	print pow(10,n-1) + (t-x)