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:
p=input()
p=p.split()
n=int(p[0])
t=int(p[1])
m=int('1'+(n-1)*'0')
q=int(n*'9')
c=0
e=0
for i in range(m,q+1):
    if i%t==0:
        c=1
        e=i
        break
if c==1:
    print(e)
else:
    print(-1)