OJ Board

Well I'll be! I've been looking at this problem for a long time. Thanks for the help!

PS
I used to post under the El-idioto pseudonym, so I'm the dummy who didn't figure out what his problem was.

Oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooohhhhhhhhhhhhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Fantastic!!!!!!!!!

This is going to be INCREDIBLY useful!!!

Yes, I realized that after BrianFry pointed me to that. But, my solution works with convex, concave, clockwise and counter-clockwise polygons. Yet there still is some sneaky input which makes my code give an incorrect answer.
I've been staring on and off at this problem for about 10 years now, and I ...

Well, I had different answers for some of the inputs, so I debugged why they were different/wrong.
After I fixed these I got accepted.

Your sample inputs found some of the errors I made.

You, my dear friend, are a life-saver!

I don't understand that.

The input is:
6 6 3 8 2 8 1 4 1 4 2 5 3
6 1 2 1 4 5 4 5 3 4 3 4 2

Please explain how your AC program calculates it to be 14.50.
Looking at my thumbnail you can see I would expect 13.50.

I get the same result for every input on the board I could find. Can someone (preferably with AC) give me their output?

Input: clg`dcbbfaabhhfabe`ba`e``ikgjbgaagfbedf`je`cccggik`fchbbidf-
`jekddajegb`gka`fidehgicffcfbghbfighkhe`ikkilkcglahdadkehfk-
cfefkkbe`dfeccklgkidakd`cg`alfjjjecagckdhedgedg ...

I keep getting WA for this problem.
Could someone please provide outputs for my inputs?

My inputs
3 0 1 3 4 6 1
3 0 3 6 3 3 0
4 0 0 0 10 10 10 10 0
4 2 2 2 7 7 7 7 2
4 2 2 2 7 7 7 7 2
4 0 0 0 10 10 10 10 0
4 0 0 0 10 10 10 10 0
4 0 0 0 5 5 5 5 0
2 5 10 10 11
2 16 4 10 16
1 0 0
1 0 0
4 20 82 97 93 ...

Here are some sample inputs and outputs for my accepted submission:

Input 7.0 -5.0 -1.0 1.0 0.0 -6.0
1.0 7.0 8.0 6.0 7.0 -2.0
5 5 4 7 16 5
56 40 66 76 31 8
44 39 26 23 37 38
18 82 29 41 33 15
0 49 19 56 98 3
7 0 11 0 9 2
0 9 0 15 3 12
0.0 0.0 1.0 0.0 0.0 2.0
6.6 2.5 -4.0 -4.0 6.6 -8.0
3.7 -4.1 3.7 ...

Thanks for testing Zobayer!

Edit:
Oh man, that's annoying. I have the same thing.
There apparently is some special case I haven't considered.

If someone knows a special case, please tell us.

Here is my source code in case someone is interested. //
// 191_Intersection: Determine whether a line ...

I have found 74 different inputs here on the boards, and all of them are correct for my program. Unfortunately, I still get WA.

Could someone with AC please try the following inputs?
500
-5 4 -3 3 4 1 -2 -4
-2 0 2 4 0 0 -1 1
1 -3 -8 -6 -3 3 3 -4
-8 -3 10 1 -5 5 3 0
0 -1 -8 -7 3 0 1 2
0 -2 -2 7 -1 ...

This is just insane! I tried submitting this problem by clicking 'Contact Us', but that link also doesn't work.
Does anyone know the email address where I can report this problem?

For a programming web-site I have to say it's awful. They should be ashamed!

I have the same problem with Presentation Error.

I tried with and without a trailing end-of-line after the last solution, but still get PE.

Input 7 3
30 3
71 13
69 3
0 0

Output ABAC ABA
7
ABAC ABCA CBAB CABA CABC ACBA CABA
28
ABAC ABAD ABAC ABAE ABAC ABAD ABAC ABAF ABAC ABAD ABAC ABAE ABAC ...