program zadanie;
var
i, z: integer;
str: string;
ch: char;
begin
WriteLn('Введите текст:');
z := 1;
ReadLn(str);
for i := 1 to length(str) do
if (str[i] = ' ') or (str[i] = '.') then
begin
if (i - z) > 3 then
begin
ch := str[i - 1];
str[i - 1] := str[z];
str[z] := ch;
end;
z := i + 1
end;
WriteLn(str);
ReadLn;
end.