%fibonachii - func1
ex2(0) -> 0;
ex2(1) -> 1;
ex2(N) ->
    ex2(N-1) + ex2(N-2).

%fibonachii - func2
ex2f(N) when N > 0 -> ex2f(N, 0, 1).
ex2f(0, F1, _F2) -> F1;
ex2f(N, F1, F2) -> ex2f(N-1, F2, F1+F2).

ex2g(N) -> (math:pow((1 + math:sqrt(5)),N) - math:pow((1 - math:sqrt(5)),N)) / (math:pow(2,N) * math:sqrt(5)).

ex2g(N) -> trunc((math:pow((1 + math:sqrt(5)),N) - math:pow((1 - math:sqrt(5)),N)) / (math:pow(2,N) * math:sqrt(5))).

ex2g(N) -> float_to_list((math:pow((1 + math:sqrt(5)),N) - math:pow((1 - math:sqrt(5)),N)) / (math:pow(2,N) * math:sqrt(5)) ,[{decimals,0}]).

** exception error: an error occurred when evaluating an arithmetic expression
     in function  math:pow/2
        called as math:pow(3.23606797749979,700)
     in call from ex:ex2g/1 (ex.erl, line 19)

21> ex:ex2f(100).               
354224848179261915075
22> ex:ex2g(100).               
"354224848179263110000"

24> ex:ex2g(100).
354224848179263111168
25> ex:ex2f(100).
354224848179261915075

2> ex:ex2f(10).
55
3> ex:ex2f(100).
354224848179261915075
4> ex:ex2f(1000).
43466557686937456435688527675040625802564660517371780402481729089536555417949051890403879840079255169295922593080322634775209689623239873322471161642996440906533187938298969649928516003704476137795166849228875
5> ex:ex2f(3000).
410615886307971260333568378719267105220125108637369252408885430926905584274113403731330491660850044560830036835706942274588569362145476502674373045446852160486606292497360503469773453733196887405847255290082049086907512622059054542195889758031109222670849274793859539133318371244795543147611073276240066737934085191731810993201706776838934766764778739502174470268627820918553842225858306408301661862900358266857238210235802504351951472997919676524004784236376453347268364152648346245840573214241419937917242918602639810097866942392015404620153818671425739835074851396421139982713640679581178458198658692285968043243656709796000
7> ex:ex2f(10000).
33644764876431783266621612005107543310302148460680063906564769974680081442166662368155595513633734025582065332680836159373734790483865268263040892463056431887354544369559827491606602099884183933864652731300088830269235673613135117579297437854413752130520504347701602264758318906527890855154366159582987279682987510631200575428783453215515103870818298969791613127856265033195487140214287532698187962046936097879900350962302291026368131493195275630227837628441540360584402572114334961180023091208287046088923962328835461505776583271252546093591128203925285393434620904245248929403901706233888991085841065183173360437470737908552631764325733993712871937587746897479926305837065742830161637408969178426378624212835258112820516370298089332099905707920064367426202389783111470054074998459250360633560933883831923386783056136435351892133279732908133732642652633989763922723407882928177953580570993691049175470808931841056146322338217465637321248226383092103297701648054726243842374862411453093812206564914032751086643394517512161526545361333111314042436854805106765843493523836959653428071768775328348234345557366719731392746273629108210679280784718035329131176778924659089938635459327894523777674406192240337638674004021330343297496902028328145933418826817683893072003634795623117103101291953169794607632737589253530772552375943788434504067715555779056450443016640119462580972216729758615026968443146952034614932291105970676243268515992834709891284706740862008587135016260312071903172086094081298321581077282076353186624611278245537208532365305775956430072517744315051539600905168603220349163222640885248852433158051534849622434848299380905070483482449327453732624567755879089187190803662058009594743150052402532709746995318770724376825907419939632265984147498193609285223945039707165443156421328157688908058783183404917434556270520223564846495196112460268313970975069382648706613264507665074611512677522748621598642530711298441182622661057163515069260029861704945425047491378115154139941550671256271197133252763631939606902895650288268608362241082050562430701794976171121233066073310059947366875

1> string:to_lower("Five Boxing WIZARDS").
"five boxing wizards"
2> string:to_upper("jump QuickLY").
"JUMP QUICKLY"

binary_to_list(X)

% строковий параметр-ключ(чи як його краще обізвати?) ~s - виводить у строковому представленні
% ~n -- це перевід строки
io:format("~s~n", [[83, 97, 109, 112, 108, 101]]).
Sample

% ~p -- у бінарному представленні
io:format("~p~n", [<<"binary білочка"/utf8>>]).
<<98,105,110,97,114,121,32,208,177,209,150,208,187,208,190,209,135,208,186,208,176>>

% ~w -- виводить без перетворення, тобто "як є", цим способом можна вивести не лише строку чи число, але й інші типи-структури ерланга у консоль
io:format("~w~n", ["Sample"]).
[83,97,109,112,108,101]

% ще є такий 
io:format("Number ~w is character ~c~n", [101, 101]).
Number 101 is character e

1> A = [1,2,5,7].
[1,2,5,7]
2> erlang:length(A).                       
4
3> lists:nth(3, A).
5
4> lists:member(8,A).
false
5> lists:member(2,A).
true
6> lists:delete(2,A).
[1,5,7]
7> A.
[1,2,5,7]

Body1 = [X || X <- Body0, X =/= $\", X=/=${, X=/=$}, X=/=$\\, X=/=$[, X=/=$]],

handle('GET',[<<"vk">>], _Req) ->
ssl:start(),
inets:start(),
Method = post,
URL = "https://api.сайт-злодій/method/users.get?user_ids=1&fields=photo_big&name_case=Nom&version=5.30",
Header = [],
Type = "application/x-www-form-urlencoded",
Body = "",
HTTPOptions = [],
Options = [],
R = httpc:request(Method, {URL, Header, Type, Body}, HTTPOptions, Options),
{ok, {Code, Head, Body0}} = R,
Body1 = [X || X <- Body0, X =/= $\", X=/=${, X=/=$}, X=/=$\\, X=/=$[, X=/=$]],
{_,Uid,_,FName,_,LName,_,P1,P2} = list_to_tuple(string:tokens(string:sub_string(Body1, 10), ",:")),
ZZ = Uid ++ ": " ++ FName ++ " " ++ LName ++ "<br><img src=\"" ++ P1 ++ ":" ++ P2 ++ "\"><br>",
R3 = erlang:list_to_binary(ZZ),
R4 = <<"суп"/utf8>>,
{ok, [{<<"Content-Type">>, <<"text/html; charset=utf-8">>}], <<"", R3/binary, R4/binary>>};

handle('GET',[<<"vk">>], _Req) ->
inets:start(),
Method = post,
URL = "http://api.сайт-злодій/method/database.getCountries?need_all=1&count=1000&v=5.52&lang=ua",
Header = [],
%Type = "application/json",
Type = "application/x-www-form-urlencoded",
Body = "",
HTTPOptions = [],
Options = [],
R = httpc:request(Method, {URL, Header, Type, Body}, HTTPOptions, Options),
{ok, {Code, Head, Body0}} = R,
R3 = erlang:list_to_binary(Body0),
{ok, [{<<"Content-Type">>, <<"text/html; charset=utf-8">>}], <<"", R3/binary>>};

-module(task).
-compile([export_all, nowarn_export_all]).


do() ->
  ssl:start(),
  %inets:start(),
  application:start(inets),
  ?MODULE:do2().

do2() ->
  Address = "https://www.google.com.ua/search?q=erlang&ie=utf-8&oe=utf-8&client=firefox-b-ab&gfe_rd=cr&dcr=0&ei=d9wiWo7aMYOK6AT-k4HACw",
  ?MODULE:get_data(Address).

get_data(Address) ->
  case httpc:request(get, {Address, 
    []}, [{ssl,[{verify,0}]}], []) of
    {ok,{_Status, _Headers , Content}} ->
      
      %io:format("~p~n",[Content]),
      %io:format("~ts~n",[Content]),
      
      ?MODULE:count_sym(Content,0);
      
    _ ->
      ?MODULE:get_data(Address)
  end,
  ssl:stop(),
  inets:stop().


count_sym([],Acc) ->
  io:format("Count: ~p~n",[Acc]);
count_sym([H|Tail],Acc) ->
  case H of
    71 ->
      % G
      ?MODULE:count_sym(Tail,Acc + 1);
    103 ->
      % g
      ?MODULE:count_sym(Tail,Acc + 1);
    _ -> ?MODULE:count_sym(Tail,Acc)
  end.