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 PYTHON):

Solution:
# your code goes here
def digits(a):
    cnt = 0
    while a>0:
        cnt += 1
        a /= 10
    return cnt

n, t = map(int, raw_input().split())
rval = 1 * pow(10, n)
val = 1
flg = 0
while val < rval:
    val *= t
    if digits(val) == n:
        flg = 1
        break

if flg:
    print val
else:
    print "-1"