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=[int(i) for i in input().split()]
lst=[]
if t<10:
    for i in range(n):
        lst.append(str(t))
    s=''.join(lst)
    print(int(s)) 
else:
    lst=[]
    s=str(t)
    lst1=list(s)
    n_digi=len(lst1)
    for i in range(n_digi):
        lst.append(lst1[i])
    n_rem=n-n_digi
    if n_digi>n:
        print(-1)
    else:
        for i in range(n_rem):
            lst.append('0')
        print(''.join(lst))