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:
#!/usr/bin/env python
#
# http://codeforces.com/problemset/problem/584/A

def compute(n, t):
	if n == 1 and t == 10:
		return '-1'
	t = str(t)
	c = t
	if c == '10': c = '1'
	for i in range(0, n - len(t)):
		t = c + t
	return t

n, t = [int(num) for num in raw_input().split()]
print(compute(n, t))