program CaesarCipher(output);

type
  Positive = 1..MaxInt;

var
  Str1: packed array [1..3] of Char;
  Str2: packed array [1..12] of Char;
  
procedure CCStr(Str: packed array [M..N: Positive] of Char);
var
  i: Integer;
begin
  for i := M to N do
    Write(Chr(Ord(Str[i]) - 1));
  Writeln;  
end;

begin
  Str1 := 'IBM';
  CCStr(Str1);
  Str2 := 'Hello,World.';
  CCStr(Str2);
end.