#!/usr/bin/python3
#
#  This program reads a text file from the standard input, and prints
#  the most common word in the input.  The words in the input are the
#  maximal-length sequences of alphabetic characters (e.g., a-z).  So,
#  a word does not include spaces or punctuation characters.
#
import sys

def line_to_words(line):
    words = []
    w = ''

    for c in line:
        if c.isalpha():
            w += c
        else:
            if not w == '':
                words.append(w)
                w = ''
    if not w == '':
        words.append(w)

    return words

D = {}

for l in sys.stdin:
    for w in line_to_words(l):
        if w in D:
            D[w] += 1
        else:
            D[w] = 1

most_common = None
max_freq = 0
for w in D:
    if D[w] > max_freq:
        most_common = w
        max_freq = D[w]

print(most_common)