SUMFOUR  4 values whose sum is 0
The SUM problem can be formulated as follows: given four lists A, B, C, D of integer values, compute how many quadruplet (a, b, c, d ) belongs to A x B x C x D are such that a + b + c + d = 0 . In the following, we assume that all lists have the same size n
Input
The first line of the input file contains the size of the lists n (this value can be as large as 4000). We then have n lines containing four integer values (with absolute value as large as 2^{28} ) that belong respectively to A, B, C and D .
Output
Output should be printed on a single line.
Example
Input: 6 45 22 42 16 41 27 56 30 36 53 37 77 36 30 75 46 26 38 10 62 32 54 6 45 Output: 5
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ranit:
20151123 08:29:36
There is a problem. I submitted the same code twice once give me TLE other give AC. It's really funny. Last edit: 20151123 08:29:55 

Lai Manh Tuan:
20151103 08:43:56
Got AC by using STL (with some optimizations).


Keshav Reddy:
20151102 22:10:45
Why does std::unordered_map give TLE? Last edit: 20151102 22:10:59 

xashru:
20151002 01:31:08
why does using


ratedx:
20150925 09:04:36
@Varun Gambhir both ordered and unordered are giving tle in my case!


kobe24:
20150905 00:30:06
Last edit: 20150905 00:52:55 

earner:
20150827 18:12:06
can anyone tell why the 10th test case is giving wrong answer?


shaky99:
20150811 12:17:08
10th test case gives WA.. can any one tell why?? Last edit: 20150811 12:18:07 

Abhinandan Agarwal:
20150804 21:52:43
Use dynamic allocation of array in case you are using binary search approach. 

Bhuvnesh Jain:
20150722 21:44:57
brilliant question with even brilliant test cases. knew that qsort() is slower than sort() in worst case complexity but never had test cases which led me to change qsort to sort.... but here CAUTION: use only sort or your own implementation of merge/heap sort... do not use quick sort at all... 
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