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 and Rodion

[n, t] = raw_input().split()

n = int(n)
t = int(t)

trial = ['1']

for i in range(0, n-1):
    trial.append('0')

lowest = ''

for char in trial:
    lowest += char

lowest = int(lowest)
largest = lowest*10

number = lowest

if number%t != 0:
    number = lowest - lowest%t + t

if number >= lowest and number < largest:
    print number
else:
    print -1