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())
min_n, max_n, possible = "1", "1", False
for i in range(1, n):
    min_n += "0"
    max_n += "1"
max_n = int(max_n)*9
min_n = int(min_n)
for i in range(min_n, max_n+1):
    if i % t == 0:
        print(i)
        possible = True
        break
if not possible:
    print(-1)