Цитата(Drenchick @ 25.05.2006 18:57)

var
 s:string;
 i,count_a,count_words:byte;

begin
 readln(s);
 i:=0;
 count_a:=0;
 count_words:=0;
 while i<=length(s) do
 begin
  inc(i);
  if s[i]='a' then
  begin 
   inc(count_a);
   repeat     
    inc(i);
    if s[i]='a' then inc(count_a);
    if count_a=3 then inc(count_words);
   until s[i]=' ';
   count_a:=0;
   dec(i);  
  end;
 end;
     
 writeln('Koluchestvo slov s 3 bykvamu a = ',count_words);
end.

var
  s: string;
  i, count_a, count_words: byte;

begin
  readln(s);
  {
    s := 'dda abbaa defaaa noneeaaaa';
  }
  count_words := 0; count_a := 0;
  for i := 1 to length(s) do
    if s[i] = 'a' then inc(count_a)
    else
      if s[i] = ' ' then begin
        if count_a = 3 then inc(count_words);
        count_a := 0;
      end;
  writeln('Koluchestvo slov s 3 bykvamu "a" = ', count_words);
end.

Цитата(Bokul @ 26.05.2006 6:34)

if s[i]='a' then begin
  inc(count_a);
  repeat    
    inc(i);
    if s[i]='a' then inc(count_a);
  until (s[i]=' ') or (i=length(s)); {Добавлен оператор or и еще одно условие}
  if count_a=3 then inc(count_words);{Перемещено}
  count_a:=0;
  dec(i);  { <--- Вот именно здесь... }
end;

...
If i < length(s) then dec(i);
...