from collections import Counter
class Mod:
    def __init__(self, file_name):
        self.file_name = file_name

    def open_file(self):
        op = open(self.file_name , 'r')

    def read_file(self):
        op = open(self.file_name, 'r')
        f1 = op.readlines()
        i=1
        for x in f1:
            if i%2==0:
                print(x)
            i += 1
    def show_lines(self):
        myNames = []

        with open(self.file_name, 'r') as f:
            for line in f:
                myNames.extend(line.split())
        print(myNames)

        dup = []
        for x in myNames:
            if myNames.count(x) > 1:
                dup.append(x)
        print(set(dup))


    def close_file(self):
        op = open(self.file_name, 'r')
        op.close()