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:
inp = input()
s = inp.find(" ")
n = int(inp[:s])
t = int(inp[s:])
if n == 1:
    i = 1
else:
    i = 10**(n-1)
b = 10**n
y = True
while i < b:
    if i%t == 0:
        print(i)
        y = False
        i = b
    i += 1
if y:
    print("-1")