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 PYTHON):

Solution:
n,t=raw_input().split(" ")
n=int(n)
t=int(t)

no10=n-1
lower=1
upper=1

while(no10>0):
    lower*=10
    no10=no10-1

upper=lower*10

flag=False

while(lower<upper):
    if(lower%t==0):
        flag=True
        break

    lower=lower+1

if(flag==True):
    print ""+str(lower)
else:
    print "-1"