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:
import math
def solve(n,t):
  if t == 10:
    if n == 1:
      return -1
    return '1'+('0'*(n-1))
  return f'{t}'*n
    
  return 

def main() :
  arr = list(map(int, input().split(' ')))
  # arr = []
  # for _ in range(3):
  #   arr.append(input())
  print(solve(*arr))
main()