Algorithms and flowcharts (Yet another C++ assignment).

Steps 4 and 5 aren't switches, you are just reading numbers.
Something like this
(pseudocode because I'm too lazy to draw a flowchart and too mean to write your actual code for you :-P )

Code:

read two numbers into i and j;
  if (both are positive) or (both are negative)
    terminate with "bad input" error;
  if (i is positive)
    place i into lineNumber and j into wordNumber;
  else
    place j into lineNumber and i into wordNumber;

The switch comes in when you have to put the word in the right place, so step 7, and it looks like this

Code:

switch (lineNumber)
{
     case 1: place the word in text.line1; break;
     case 2: place the word in text.line2; break;
     case 3:....
     default: exit with "bad input" error;
}

(note that this is butt-ugly and I hope the purpose of the exercise is to show you how much unnecessary work you have to do when you choose the wrong data structure).