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:
import sys 
def get_ints():
	return map(int, sys.stdin.readline().strip().split()) 
n,t= get_ints()
zero ='0'
zero*=n-1
an='1'+zero
start= int(an)
en = '9'*n
end = int(en)
find =False
for i in range(start, end+1):
	if(i%t==0):
		print(i)
		find = True
		break
if(find==False):
	print(-1)