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=input().split()
n=int(n)
t=int(t)
number_min='1'
number_max='10'
for i in range(0,n-1,1):
    number_min=number_min+'0'
    number_max=number_max+'0'
number_min=int(number_min)
number_max=int(number_max)-1
result=-1
for i in range(number_min,number_max+1,1):
    
    if i%t==0:
        result=i
        break
print(result)