Score: 600 points
We have N non-negative integers: A_1, A_2, ..., A_N.
Consider painting at least one and at most N-1 integers among them in red, and painting the rest in blue.
Let the beauty of the painting be the \mbox{XOR} of the integers painted in red, plus the \mbox{XOR} of the integers painted in blue.
Find the maximum possible beauty of the painting.
The bitwise \mbox{XOR} x_1 \oplus x_2 \oplus \ldots \oplus x_n of n non-negative integers x_1, x_2, \ldots, x_n is defined as follows:
Input is given from Standard Input in the following format:
N A_1 A_2 ... A_N
Print the maximum possible beauty of the painting.
3 3 6 5
12
If we paint 3, 6, 5 in blue, red, blue, respectively, the beauty will be (6) + (3 \oplus 5) = 12.
There is no way to paint the integers resulting in greater beauty than 12, so the answer is 12.
4 23 36 66 65
188
20 1008288677408720767 539403903321871999 1044301017184589821 215886900497862655 504277496111605629 972104334925272829 792625803473366909 972333547668684797 467386965442856573 755861732751878143 1151846447448561405 467257771752201853 683930041385277311 432010719984459389 319104378117934975 611451291444233983 647509226592964607 251832107792119421 827811265410084479 864032478037725181
2012721721873704572
A_i and the answer may not fit into a 32-bit integer type.