import time

start_time = time.time()

f = open('names_1.txt', 'r')
names_1 = f.read().split("\n")  # List containing 10000 names
f.close()

f = open('names_2.txt', 'r')
names_2 = f.read().split("\n")  # List containing 10000 names
f.close()

duplicates = []
dictionary = {}
for name_1 in names_1:
  dictionary[name_1] = name_1
for name_2 in names_2:
  try:
    duplicates.append(dictionary[name_2])
  except KeyError:
    pass
    

end_time = time.time()
print (f"{len(duplicates)} duplicates:\n\n{', '.join(duplicates)}\n\n")
print (f"runtime: {end_time - start_time} seconds")