Buggy python submission (verdict: Time Limit Exceeded):
#input
N = int(input())
A = list(map(int, input().split()))

#output
# Python program to find
# maximum XOR subset

# Number of bits to
# represent int
INT_BITS = 64

# Function to return
# maximum XOR subset
# in set[]
def maxSubarrayXOR(set,n):

	# Initialize index of
	# chosen elements
	index = 0

	# Traverse through all
	# bits of integer
	# starting from the most
	# significant bit (MSB)
	for i in range(INT_BITS-1,-1,-1):

		# Initialize index of
		# maximum element and
		# the maximum element
		maxInd = index
		maxEle = -9223372036854775808
		for j in range(index,n):

			# If i'th bit of set[j]
			# is set and set[j] is
			# greater than max so far.
			if ( (set[j] & (1 << i)) != 0
					and set[j] > maxEle ):

				maxEle = set[j]
				maxInd = j

		# If there was no
		# element with i'th
		# bit set, move to
		# smaller i
		if (maxEle == -9223372036854775808):
			continue

		# Put maximum element
		# with i'th bit set
		# at index 'index'
		temp = set[index]
		set[index] = set[maxInd]
		set[maxInd] = temp

		# Update maxInd and
		# increment index
		maxInd = index

		# Do XOR of set[maxIndex]
		# with all numbers having
		# i'th bit as set.
		for j in range(n):

			# XOR set[maxInd] those
			# numbers which have the
			# i'th bit set
			if (j != maxInd and
			(set[j] & (1 << i)) != 0):
				set[j] ^= set[maxInd]

		# Increment index of
		# chosen elements
		index += 1

	# Final result is
	# XOR of all elements
	res = 0
	for i in range(n):
		res ^= set[i]
	return res

B = 0
for i in range(N):
	B ^= A[i]

A2 = [a&(~B) for a in A]
d = maxSubarrayXOR(A2, N)

print(int(d) + int(B^d))

Fixed submission:
#input
N = int(input())
A = list(map(int, input().split()))

#output
# Python program to find
# maximum XOR subset

# Number of bits to
# represent int
INT_BITS = 64

# Function to return
# maximum XOR subset
# in set[]
def maxSubarrayXOR(set,n):

	# Initialize index of
	# chosen elements
	index = 0

	# Traverse through all
	# bits of integer
	# starting from the most
	# significant bit (MSB)
	for i in range(INT_BITS-1,-1,-1):

		# Initialize index of
		# maximum element and
		# the maximum element
		maxInd = index
		maxEle = -9223372036854775808
		for j in range(index,n):

			# If i'th bit of set[j]
			# is set and set[j] is
			# greater than max so far.
			if ( (set[j] & (1 << i)) != 0
					and set[j] > maxEle ):

				maxEle = set[j]
				maxInd = j

		# If there was no
		# element with i'th
		# bit set, move to
		# smaller i
		if (maxEle == -9223372036854775808):
			continue

		# Put maximum element
		# with i'th bit set
		# at index 'index'
		temp = set[index]
		set[index] = set[maxInd]
		set[maxInd] = temp

		# Update maxInd and
		# increment index
		maxInd = index

		# Do XOR of set[maxIndex]
		# with all numbers having
		# i'th bit as set.
		for j in range(n):

			# XOR set[maxInd] those
			# numbers which have the
			# i'th bit set
			if (j != maxInd and
			(set[j] & (1 << i)) != 0):
				set[j] ^= set[maxInd]

		# Increment index of
		# chosen elements
		index += 1

	# Final result is
	# XOR of all elements
	res = 0
	for i in range(n):
		res ^= set[i]
	return res

B = 0
for a in A:
	B ^= a

A2 = [a&(~B) for a in A]
d = maxSubarrayXOR(A2, N)

print(int(d) + int(B^d))