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,r=input().split()
n=int(n)
r=int(r)
if 2<=r<=9:
    a=[r]*n
    b=int(''.join(map(str, a)))
    if b%r==0:
        print(b)
elif r==10:
    c=[1]+[0]*(n-1)
    d=int(''.join(map(str, c)))
    if n>1 and d%r==0:
        print(d)
    else:
        print('-1')