Even if this problem isn't homework (this is becoming a tired phrase...), you might benefit from tackling this problem yourself.

Split the problem into pieces.

My solution is a little messy, but I'll give you a few hints.

• Use Super search to look up how to read lines from a file
• Consider using a conditional loop:

  if (condition) {
   # do something
  }
  [download]

• Assign the number on the line you've read to a variable (for example: $number)
• Assign a 0 or 1 to another variable and keep track of whether or not you've divided or not.($divide_p)
• Figure the rest out.