This is my code:

{$APPTYPE CONSOLE}
uses
  SysUtils;
var
   s: string;
   f: boolean;
   newstr: string;
   i: integer;

begin
 //assign(input, 'input.txt'); reset(input);
// assign(output, 'output.txt'); rewrite(output);

 f:=true;
  while not eof do
   begin
    readln(s);
    newstr:='';
    s:=LowerCase(s);
    // process

     for i:=1 to length(s) do
      begin
       if f and (s[i] <> ' ') and (s[i] <> ',') and (s[i] <> '!')
            and (s[i] <> '?') and (s[i] <> '.') then
       begin
        newstr:=newstr + UpCase(s[i]);
        f:= false;
       end
       else newstr:=newstr + s[i];

       if (s[i] = '?') or (s[i] = '!') or (s[i] = '.') then
             f:=true;
      end;
     writeln(newstr);
   end;

end.