import re

S = input()

w = 'ｗ'
reg = re.compile('^[^ｗ]*ｗ+')
s = S
cands = []
while m := reg.match(s):
    t = m.group(0)
    if t[0] != w:
        cands.append((t, t.count(w)))
    s = s[len(t):]

if not cands:
    print()
    exit()

_, max_wcnt = max(cands, key=lambda x: x[1])
for s, wcnt in cands:
    if wcnt == max_wcnt:
        print(s[:-wcnt])