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:
nt = input().split(" ")
n = int(nt[0])
t = int(nt[1])
start = '1'
end = '9'
for i in range(n-1):
    start += '0'
    end += '9'
for i in range(int(start), int(end)+1):
    if(i > 0 and i % t == 0) :
        print(i)
        break
if(i >= int(end) and i % t != 0) :
        print('-1')