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())
if t!=10:
 no=['1']
 for i in range(n-1) :
    no.append(str(0))

 nom="".join(no)
 print(int(nom)*t)

else :
    no = ['1']
    for i in range(n - 1):
        no.append(str(0))

    nom = "".join(no)
    if int(nom)%10==0:
     print(int(nom))
    else:
        print("-1")