main.pas

program rot13;
var
   input: string;
   i: integer;

function ROT13(c: char): char;
begin
   if c in ['A'..'Z'] then
      ROT13 := chr((ord(c) - ord('A') + 13) mod 26 + ord('A'))
   else if c in ['a'..'z'] then
      ROT13 := chr((ord(c) - ord('a') + 13) mod 26 + ord('a'))
   else
      ROT13 := c;
end;

begin
   write('Enter string to encode: ');
   read(input);

   write('Encoded string: ');
   for i := 1 to length(input) do
      write(ROT13(input[i]));

   writeln;
end.