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:
# Author: Mariana Mendes.
# Problem 584A  The number of positions*/
   
   
n = map(long,raw_input().split(" "))
fim = long('9' * n[0])
ans = -1


while len(str(fim)) >= n[0] and fim != 0:
	if(fim%n[1] == 0):
		
			ans = fim
			break
	else:
		fim-=1
		
print ans