s = input()
l = len(s)
d = []
w = 'ｗ'
a = 0
for i in range(l):
    if s[i] == w:
        continue
    if i != 0 and s[i-1] != w:
        continue
    t = ""
    j = i
    while j < l and s[j] != w:
        t += s[j]
        j += 1
    k = 0
    while j < l and s[j] == w:
        #t += s[j]
        j += 1
        k += 1
    if a < k:
        a = k
        d = []
    if a == k:
        d.append(t)

if a == 0:
    d = []
    
for x in d:    
    print(x)