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:
# n digit
# t divisor

from sys import stdin

n, t = [int(c) for c in stdin.readline().split()]

# ll low limit
# higt limit

hl = 10 ** (n) - 1


while True:
    if hl % t == 0:
        y = hl / t
        break
    else:
        hl = hl - 1

if hl<t:
    print(-1)
else:
    print(hl)