import os
 
## Move into the directory where the database is.
os.chdir('folder where file is')
 
open_file = open('candidates.txt', 'r')
line = open_file.readline()
name = line.strip()
 
candidateDict = {}
 
def find_duplicate():
    for name in open_file:
        if candidateDict.has_key(name):
            candidateDict[name] += 1
        else:
            candidateDict[name] = 1
 
find_duplicate()
 
for name in candidateDict:
    if candidateDict[name] > 1:
        print name
 
open_file.close()