Word Subtraction

program WordSubtraction;

procedure subtractWords(shortWord, longWord: string);
var
  count: integer;
  result: string;
begin
  for count := 1 to length(shortWord) do
      result := concat(result, chr((ord(longWord[count]) - ord(shortWord[count]) + 25) mod 26 + 65));
  result := concat(result, copy(longWord, length(shortWord) + 1, length(longWord) - length(shortWord) - 1));
  writeln('Result: ', result);
end;

procedure main();
var
  word1, word2: string;
begin
  write('Enter a word: ');
  readln(word1);
  write('Enter another word: ');
  readln(word2);
  if length(word1) > length(word2) then
    subtractWords(upcase(word2), upcase(word1))
  else
    subtractWords(upcase(word1), upcase(word2));
end;

begin
  main();
  readln;
end.