% Enter your code here. Read input from STDIN. Print output to STDOUT
% Your class should be named solution

% https://www.hackerrank.com/contests/projecteuler/challenges/euler019

-module(solution).
-export([main/0, prof/0]).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Main
%%%%%%%%%%%%%%%%%%%%%%%%%%%%

main() ->
    Data = read_data(),
    Res = calculate(Data),
    output_data(Res),
    ok.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Profiling
%%%%%%%%%%%%%%%%%%%%%%%%%%%%

prof() ->
    eprof:start(),
    eprof:start_profiling([self()]),
    main2(),
    eprof:stop_profiling(),
    eprof:analyze(total). 

main2() ->
    StartInput = os:timestamp(),
    Data = read_data(),
    io:format("INPUT: total time taken ~p seconds~n", [timer:now_diff(os:timestamp(), StartInput)/1000000]),
    StartRes = os:timestamp(),
    Res = calculate(Data),
    io:format("CALCULATE: total time taken ~p seconds~n", [timer:now_diff(os:timestamp(), StartRes)/1000000]),
    StartOutput = os:timestamp(),
    output_data(Res),
    io:format("OUTPUT: total time taken ~p seconds~n", [timer:now_diff(os:timestamp(), StartOutput)/1000000]),
    ok.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Calculate
%%%%%%%%%%%%%%%%%%%%%%%%%%%%

calculate(Pos) ->
    lists:map(fun check/1, Pos).

check([H|T]) ->
    check(T, {H, none}).

check([{X, Y}|T], {{X1, Y1}, Ref2}) ->
    case ((X == X1) or (Y == Y1)) of 
        true ->
            check(T, {{X1, Y1}, Ref2});
        false ->
            case Ref2 of 
                none ->
                    check(T, {{X1, Y1}, {X, Y}});
                {X2, Y2} ->
                    case ((X == X2) or (Y == Y2)) of 
                        true ->
                            check(T, {{X1, Y1}, Ref2});
                        false ->
                            false 
                    end 
            end 
    end;
check([], _) ->
    true.


%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Output
%%%%%%%%%%%%%%%%%%%%%%%%%%%%

output_data(Ds) -> 
    lists:map(
        fun(D) -> io:format("~s\n", [case D of true -> "YES"; false -> "NO" end]) end, 
        Ds).

%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Input
%%%%%%%%%%%%%%%%%%%%%%%%%%%%

read_data() ->
    Binary = read(),
    Res = binary:split(Binary, [<<"\n">>], [global]),
    [_| Tests] = [binary_to_list(R) || R <- Res],
    read_tests(Tests, []).

read_tests([NStr | T], Acc) ->
    N = str2int(NStr),
    {Pos, RT} = read_pos(T, N, []),
    read_tests(RT, [Pos | Acc]);
read_tests([], Acc) ->
    lists:reverse(Acc).

read_pos(L, 0, Acc) ->
    {Acc, L};
read_pos([Pos | T], N, Acc) ->
    [X,Y] = str2intlist(Pos),
    read_pos(T, N - 1, [{X, Y} | Acc]).

str2intlist(S) ->
    [str2int(T) || T <- string:tokens(S, " ")].

str2int(Str) ->
    element(1,string:to_integer(Str)).

-define(BLK_SIZE, 16384).

read() ->
    ok = io:setopts(standard_io, [binary]),
    read(<<>>).

read(Acc) ->
    case file:read(standard_io, ?BLK_SIZE) of
        {ok, Data} ->
            read(<<Acc/bytes, Data/bytes>>);
        eof ->
            Acc
    end.

ed(T) ->    
    erlang:display(T).