participant = ["john", "stanko", "mislav", "ana"]
completion = ["stanko", "ana", "mislav"]

count = {}

for name in participant:
    if name in count:
        count[name] += 1
    else:
        count[name] = 1

for name in completion:
    count[name] -= 1

for name in count:
    if count[name] != 0:
        print(name)
        break