user = input()

words01 = user.split(" ")

words02 = set(words01)

temp_result = []
for word in words02:
    temp_result.append([word, words01.count(word)])

popular_words = sorted(temp_result, key = lambda x : x[1], reverse=True)

result = []
count = popular_words[0][1]
for word in popular_words:
    if count == word[1]:
        result.append(word[0])
result_sort = sorted(result)
print(result_sort[0])