Buggy python submission (verdict: Time Limit Exceeded):
def main():
  import collections
  import sys
  input = sys.stdin.readline
  n = int(input())
  b = []
  for i in range(n):
    a = int(input())
    b_append = b.append
    b_append(a)

  s = set(b)
  c = collections.Counter(b)
  ans = 0
  for i in range(len(s)):
    if c.most_common()[i][1] % 2 == 0:
      continue
    else:
      ans += 1
    if c.most_common()[i][1] == 1:
      ans += len(s)-1-i
      break
  print(ans)
if __name__ == '__main__':
    main()

Fixed submission:
n = int(input())
a = []
for i in range(n):
  a.append(int(input()))
a.sort()
b = []
for i in range(0,n-1,2):
  if a[i] != a[i+1]:
    b.append(a[i])
    b.append(a[i+1])
  else:
    continue
if n%2 == 1:
  b.append(a[-1])
#print(b)
ans = []
if b != []:
  ans.append(b[0])
  for j in range(1,len(b)-1,2):
    if b[j] != b[j+1]:
      ans.append(b[j])
      ans.append(b[j+1])
  if len(b)%2 == 0:
    ans.append(b[-1])
#print(ans)
if ans == []:
  print(0)
else:
  print(len(ans))

Buggy python submission (verdict: Runtime Error):
import collections
import sys
input = sys.stdin.readline
n = int(input())
b = []
for i in range(n):
  a = int(input())
  b_append = b.append
  b_append(a)

s = set(b)
c = collections.Counter(b)
ans = 0
for i in range(n-len(s)):
  if c.most_common()[i][1] % 2 == 0:
    ans -= 1
ans += len(s)
print(ans)

Fixed submission:
n = int(input())
a = []
for i in range(n):
  a.append(int(input()))
a.sort()
b = []
for i in range(0,n-1,2):
  if a[i] != a[i+1]:
    b.append(a[i])
    b.append(a[i+1])
  else:
    continue
if n%2 == 1:
  b.append(a[-1])
#print(b)
ans = []
if b != []:
  ans.append(b[0])
  for j in range(1,len(b)-1,2):
    if b[j] != b[j+1]:
      ans.append(b[j])
      ans.append(b[j+1])
  if len(b)%2 == 0:
    ans.append(b[-1])
#print(ans)
if ans == []:
  print(0)
else:
  print(len(ans))

Buggy python submission (verdict: Time Limit Exceeded):
import collections
import sys
input = sys.stdin.readline
n = int(input())
b = []
for i in range(n):
  a = int(input())
  b_append = b.append
  b_append(a)

s = set(b)
c = collections.Counter(b)
ans = 0
for i in range(len(s)):
  if c.most_common()[i][1] % 2 == 0:
    continue
  else:
    ans += 1
  if c.most_common()[i][1] == 1:
    ans += len(s)-1-i
    break
print(ans)

Fixed submission:
n = int(input())
a = []
for i in range(n):
  a.append(int(input()))
a.sort()
b = []
for i in range(0,n-1,2):
  if a[i] != a[i+1]:
    b.append(a[i])
    b.append(a[i+1])
  else:
    continue
if n%2 == 1:
  b.append(a[-1])
#print(b)
ans = []
if b != []:
  ans.append(b[0])
  for j in range(1,len(b)-1,2):
    if b[j] != b[j+1]:
      ans.append(b[j])
      ans.append(b[j+1])
  if len(b)%2 == 0:
    ans.append(b[-1])
#print(ans)
if ans == []:
  print(0)
else:
  print(len(ans))

Buggy python submission (verdict: Runtime Error):
n = int(input())
a = []
for i in range(n):
  a.append(int(input()))
a.sort()
b = []
for i in range(0,n-1,2):
  if a[i] != a[i+1]:
    b.append(a[i])
    b.append(a[i+1])
  else:
    continue
if n%2 == 1:
  b.append(a[-1])
#print(b)
ans = []
if b != []:
  ans.append(b[0])
  for j in range(1,len(b)-1,2):
    if b[j] != b[j+1]:
      ans.append(b[i])
      ans.append(b[i+1])
#print(ans)
if ans == []:
  print(0)
else:
  print(len(ans))

Fixed submission:
n = int(input())
a = []
for i in range(n):
  a.append(int(input()))
a.sort()
b = []
for i in range(0,n-1,2):
  if a[i] != a[i+1]:
    b.append(a[i])
    b.append(a[i+1])
  else:
    continue
if n%2 == 1:
  b.append(a[-1])
#print(b)
ans = []
if b != []:
  ans.append(b[0])
  for j in range(1,len(b)-1,2):
    if b[j] != b[j+1]:
      ans.append(b[j])
      ans.append(b[j+1])
  if len(b)%2 == 0:
    ans.append(b[-1])
#print(ans)
if ans == []:
  print(0)
else:
  print(len(ans))

Buggy python submission (verdict: Runtime Error):
n = int(input())
a = []
for i in range(n):
  a.append(int(input()))
a.sort()
b = []
for i in range(0,n-1,2):
  if a[i] != a[i+1]:
    b.append(a[i])
    b.append(a[i+1])
  else:
    continue
if n%2 == 1:
  b.append(a[-1])
print(b)
ans = []
if b != []:
  ans.append(b[0])
  for j in range(1,len(b)-1,2):
    if b[j] != b[j+1]:
      ans.append(b[i])
      ans.append(b[i+1])
print(ans)
if ans == []:
  print(0)
else:
  print(len(ans))

Fixed submission:
n = int(input())
a = []
for i in range(n):
  a.append(int(input()))
a.sort()
b = []
for i in range(0,n-1,2):
  if a[i] != a[i+1]:
    b.append(a[i])
    b.append(a[i+1])
  else:
    continue
if n%2 == 1:
  b.append(a[-1])
#print(b)
ans = []
if b != []:
  ans.append(b[0])
  for j in range(1,len(b)-1,2):
    if b[j] != b[j+1]:
      ans.append(b[j])
      ans.append(b[j+1])
  if len(b)%2 == 0:
    ans.append(b[-1])
#print(ans)
if ans == []:
  print(0)
else:
  print(len(ans))