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:
#-*- encoding:utf-8 -*-






'''

n : 자리수
t : 나눠지는 숫자

3 2
3자리수 중 2로 나눠지는 숫자 아무거나...998, 222, 등등등

'''

n, t = map(int, raw_input().split())

if n != 1 or t != 10 :
	print (10**n-1)/t*t	#3,2 라고 했을때, 999/2 -> 499 *2 -> 998 안나눠지는 나머지 숫자를 떼어낼수 있음...
else:
	print -1