import random
import time
import copy
import io, sys

s = input()

list1 = []
buf = []
cnt = 0
for c in s:
    if (c == 'ｗ'): cnt += 1 
    elif (c != 'ｗ' and cnt != 0):
        if (len(buf) > 0):
            list1.append((''.join(buf), cnt))
        buf = [c]
        cnt = 0
    else: buf.append(c)
if (cnt != 0):
    list1.append((''.join(buf), cnt))

list1.sort(key=lambda t:t[1], reverse=True)

#print(list1)
if (len(list1) > 0 and list1[0][1] > 0):
    for t in list1:
        if (t[1] != list1[0][1]):
            break
        if (t[0] != ""): print(t[0])