.function longest_a_string(input : string) : string;
var i, maxLen, maxIndex, currentLen : integer;
begin
maxLen := 0;
currentLen := 0;
maxIndex := 0;
for i := 1 to length(input) do
if (input[i] = 'a') then
begin
currentLen := currentLen + 1;
if (currentLen > maxLen) then
begin
maxLen := currentLen;
maxIndex := i;
end;
end
else
currentLen := 0;
if (maxLen > 0) then
longest_a_string := copy(input, maxIndex - maxLen + 1, maxLen)
else
longest_a_string := '';
end;
