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:
import math 

s = raw_input()
a, b = s.split()

ndig = int(a)
divisor = int(b)
lower_bnd = 10**(ndig - 1) / divisor + 1
upper_bnd = (10**ndig - 1) / divisor
if lower_bnd > upper_bnd or lower_bnd <=0 or upper_bnd <= 0:
    print -1
else:
    print int(divisor * lower_bnd)