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:
x, t = map(int, input().split())
if t == 10 and x == 1: print(-1); exit()
n = x-1
tmp = 1
while(n):
    tmp *= 10
    tmp = tmp%t
    n -= 1
if tmp == 0: tmp = t
if x == 1: print(t)
else: print('1'+'0'*(x-2)+str(t-tmp))