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,m = [int(x) for x in input().split()]
a = [1]*n
b = 0
if m == 10:
    a[-1] = 0
else:
    for i in range(n):
        b += 10**i
    t = b%m
    if t != 0:
        a[-1] += (m-t)

if n == 1 and m == 10:
    print(-1)
else:
    for elem in a:
        print(elem,end='')