S = input()
i, mx = 0, 0
n = len(S)
stk = ''
ans = []
while i < n:
    p = i
    while i < n and S[i] == S[p]:
        i += 1
    if S[p] == 'ｗ':
        if i - p > mx:
            mx = i - p
            ans.clear()
        if i - p == mx:
            ans.append(stk)
        stk = ''
    else:
        for j in range(p, i):
            stk += S[j]

for s in ans:
    print(s)