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)
i=0
flag=0
num=1
while (i<n-1):
    num*=10
    i+=1
tem=num
while (num<tem*10):
    if (num%t==0):
        flag=1
        break
    num+=1
if (flag==0 or n==0):
    print -1
elif (flag==1):
    print num