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=map(int,raw_input().split())
s=[]
s.append('1')
for i in range(1,n):
          s.append('0')
s=''.join(s)
s=int(s)
c=1
s=s+1
while 1:
          if s%t==0:
                    break
          else:
                    s=s+1
                    a=str(s)
                    if len(a)>n:
                              c=0
                              break
if c==0:
          print '-1'
else:
          print s