#!/bin/sh
""""exec ${PYTHON:-python} -t $0 "$@";" """
# vim: filetype=python expandtab smarttab shiftwidth=4


import sys
import string
from operator import itemgetter as nth


alphanumerics = string.lowercase + string.digits

def emit_top_new(paragraph, show_count, previous, keep_previous_count):
    """Given some text and a list of disallowed characters, return two samples
    of the most common letters.  One sample is likely to be fed back in as a
    disallowed list.

    >>> emit_top_new("", 3, ['1', '2'], 2)
    ([], [])
    >>> emit_top_new("abcdefghighighijkljklmnopppp", 3, [], 2)
    (['p', 'h', 'i'], ['p', 'h'])
    >>> emit_top_new("abcdefghighighijkljklmnopppp", 3, ['p', 'h'], 2)
    (['i', 'g', 'l'], ['i', 'g'])
    """
    character_count = dict([c, 0] for c in alphanumerics)

    for c in previous:
        character_count.pop(c, None)

    for c in paragraph.lower():
        try:
            character_count[c] += 1
        except KeyError:
            pass  # not a character we care about

    sortable = character_count.items()

    sortable.sort(key=nth(1))
    sortable.reverse()
    sortable = [k for k, v in sortable if v > 0]

    return sortable[:show_count], sortable[:keep_previous_count]


if __name__ == "__main__":
    import doctest
    doctest.testmod()

    show_count = 10
    keep_previous_count = 5
    previous = set()

    lines = []
    for line in sys.stdin:
        if line.strip() == "":
            if lines:
                new, previous = emit_top_new("".join(lines), show_count, previous, keep_previous_count)
                print new
                lines = []
        else:
            lines.append(line)

    if lines:
        new, previous = emit_top_new("".join(lines), show_count, previous, keep_previous_count)
        print new