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:
#olesya

n1, n2 = map(int, raw_input().split())

if n2 == 10 and n1 == 1:
	n3 = -1
elif n2 == 10 and n1 > 1:
	n3 = str(n2) + (n1 - 2) * '0'
else:
	n3 = str(n2) + (n1-1) * '0'

print int(n3)