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
import sys

def crea(digit, n):
  s = ""
  for i in range(n):
    s += digit
  return s
     

line = input()
r = [int(x) for x in line.split()]
n = r[0]
t = r[1]

if(t == 3 or t == 9):
  resp = crea('9', n)
elif (t == 10):
  if(n == 1):
    resp = -1
  else:
    resp = crea('1', n-1)+"0"
elif (t == 5 or t == 7):
  resp = crea(str(t), n)
elif (t == 2 or t == 4 or t == 8):
  resp = crea('8', n)
elif (t == 6):
  resp = crea('3', n-1)+"6"
print(resp)