Using dictionary

 K = int(input())
L = map(int, input().split(' '))

D = dict()

for x in L:
    if D.get(x) == None:
        D[x] = 1
    else:
        D[x] += 1

for x in D:
    if D[x] == 1:
        print(x)

idk why it didn't work (only passed 1 scenario) but:

num = input() roomlist = input() rlit = roomlist.split() rlit_int = list(map(int, rlit))

while len(rlit_int) > 1: x = rlit_int[0] while x in rlit_int: rlit_int.remove(x)

print(rlit_int[0])

Failed in Scenario 0

k = int(input()) klist = list(map(int, input().split()))

lenlist = int(len(klist)/2)

set1 = set([x for x in klist[:lenlist]]) set2 = set([x for x in klist[lenlist+1:]])

captainroom = (set1 ^ set2)

print(list(captainroom)[0])

print(captainroom[0])

Solution with only implement set concept

k = int(input())
rooms = list(map(int, input().split()))

unique_room = sum(set(rooms))
total_rooms = sum(rooms)

print((k*unique_room-total_rooms)//(k-1))

from collections import Counter k=int(input()) ABC = Counter(input().split()) for item,value in ABC.items(): if value==1: print(item)