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

if N==1:
  if K%2:
    print(A[0])
  else:
    print('')
  exit()
  

#print(*range(10000))

def func(L):
  s = []
  for l in L:
    if l in s:
      del s[s.index(l):]
      #s_set.remove(l)
    else:
      s.append(l)
      #s_set.add(l)
  return s




index_dict={}
for i,a in enumerate(A):
  index_dict.setdefault(a,[]).append(i)

next_i = [0]*N
cycle_i = [0]*N
for k,v in index_dict.items():
  for i in range(len(v)):
    next_i[v[i]] = (v[(i+1)%len(v)]+1)%N
    cycle_i[v[i]] = (i+1)//len(v)

from_in_cycle=[]

i = 0
while True:
  j = next_i[i]
  if cycle_i[i]:
    from_in_cycle.append(i)
  i = j
  # 循環の評価
  if i==0:
    break
    
#print(from_in_cycle)

if from_in_cycle:
  k = K%(len(from_in_cycle)+1)
  print(*func(A[from_in_cycle[k-1]:]))
else:
  print('')

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

if N==1:
  if K%2:
    print(A[0])
  else:
    print('')
  exit()
  

#print(*range(10000))

def func(L):
  s = []
  for l in L:
    if l in s:
      del s[s.index(l):]
      #s_set.remove(l)
    else:
      s.append(l)
      #s_set.add(l)
  return s




index_dict={}
for i,a in enumerate(A):
  index_dict.setdefault(a,[]).append(i)

next_i = [0]*N
cycle_i = [0]*N
for k,v in index_dict.items():
  for i in range(len(v)):
    next_i[v[i]] = (v[(i+1)%len(v)]+1)%N
    cycle_i[v[i]] = (i+1)//len(v)
#print(next_i)
#print(cycle_i)

from_in_cycle=[]

i = 0
while True:
  j = next_i[i]
  if cycle_i[i]:
    from_in_cycle.append(i)
  i = j
  # 循環の評価
  if i==0:
    break
    
#print(from_in_cycle)

if from_in_cycle:
  k = K%(len(from_in_cycle)+1)
  #print(*func(A[from_in_cycle[k-1]:]))

  ans = []
  i = from_in_cycle[k-1]
  while i < N:
    if cycle_i[i]:
      ans.append(A[i])
      i += 1
    else:
      if next_i[i]==0:
        break
      i = next_i[i]
  print(*ans)


else:
  print('')

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

if N==1:
  if K%2:
    print(A[0])
  else:
    print('')
  exit()
  

#print(*range(10000))

def func(L):
  s = []
  for l in L:
    if l in s:
      del s[s.index(l):]
      #s_set.remove(l)
    else:
      s.append(l)
      #s_set.add(l)
  return s

index_dict={}

for i,a in enumerate(A):
  index_dict.setdefault(a,[]).append(i)

#print(index_dict)

from_in_cycle=[]

i = 0
while True:
  a = A[i]
  l = len(index_dict[a])
  j = index_dict[a].index(i)
  if j==l-1:
    from_in_cycle.append(i)
    i = (index_dict[a][0]+1)%N
  else:
    i = (index_dict[a][j+1]+1)%N
  # 循環の評価
  if i==0:
    break
    
#print(from_in_cycle)

if from_in_cycle:
  k = K%(len(from_in_cycle)+1)
  print(*func(A[from_in_cycle[k-1]:]))
else:
  print('')

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

if N==1:
  if K%2:
    print(A[0])
  else:
    print('')
  exit()
  

#print(*range(10000))

def func(L):
  s = []
  for l in L:
    if l in s:
      del s[s.index(l):]
      #s_set.remove(l)
    else:
      s.append(l)
      #s_set.add(l)
  return s




index_dict={}
for i,a in enumerate(A):
  index_dict.setdefault(a,[]).append(i)

next_i = [0]*N
cycle_i = [0]*N
for k,v in index_dict.items():
  for i in range(len(v)):
    next_i[v[i]] = (v[(i+1)%len(v)]+1)%N
    cycle_i[v[i]] = (i+1)//len(v)
#print(next_i)
#print(cycle_i)

from_in_cycle=[]

i = 0
while True:
  j = next_i[i]
  if cycle_i[i]:
    from_in_cycle.append(i)
  i = j
  # 循環の評価
  if i==0:
    break
    
#print(from_in_cycle)

if from_in_cycle:
  k = K%(len(from_in_cycle)+1)
  #print(*func(A[from_in_cycle[k-1]:]))

  ans = []
  i = from_in_cycle[k-1]
  while i < N:
    if cycle_i[i]:
      ans.append(A[i])
      i += 1
    else:
      if next_i[i]==0:
        break
      i = next_i[i]
  print(*ans)


else:
  print('')