def search(data_set,find_num):

    mid = len(data_set) /2

    print mid

    if len(data_set) == 1:

       if data_set[mid] == find_num:

        print ('End start: ',find_num)

        return

       else:

        print ('NO NO NO:',find_num)

        return

    if data_set[mid] == find_num:

        print ('find start:',find_num)

        return

    elif data_set[mid] > find_num:

        print ('in left',data_set[:mid])

        search(data_set[:mid],find_num)

    elif  data_set[mid] < find_num:

        print ('in right',data_set[mid:])

        search(data_set[mid:],find_num)

if __name__ == '__main__':

    data = range(1,20,3)

    print (data)

    find = input('num:')

    search(data,find)