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:
__author__ = 'yarsanich'
n, t = map(int, input().split())
s_min = '1'
for i in range(n - 1):
    s_min = s_min + '0'
s_max = ''
for i in range(n):
    s_max = s_max + '9'
ans = -1
# print(s_min, s_max)
for i in range(int(s_min), int(s_max)):
    if (i % t == 0):
        ans = i;
        break
if (n == 1):
    for i in range(10):
        if (i % t == 0): ans = i
if (ans == 0):
    print(-1)
else:
    print(ans)