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, t = map(int, input().split())
nach = int('1' + (n-1)*'0')
kon = int(str(nach) + '0') - 1
rez = 0
while (rez == 0) and (nach <= kon):
    if nach % t == 0:
        rez = nach
        nach += 1
    else:
        nach += 1
if rez == 0:
    print(-1)
else:
    print(rez)