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:
nt=[int(i) for i in input().split()]
n=nt[0]
t=nt[1]
number=[]
if n==1:
    if t==10:
        print(-1)
    else:
        print(t)
if n>=2:
    number.append('1')
    for i in range(n-2):
        number.append('0')
    for i in range(10):
        if int(''.join(number)+str(i))%t==0:
            print(''.join(number)+str(i))
            break