s = input()
tmp = 0
l, last = 0, 0
ans = []
while l < len(s):
    if s[l] != 'ｗ':
        l += 1
        continue
    r = l
    while r < len(s) and s[l] == s[r]:
        r += 1
    if r - l == tmp and l - last > 0:
        ans.append(s[last:l])
    elif r - l > tmp and l - last > 0:
        ans = [s[last:l]]
        tmp = r - l
    last = r
    l = r
print("\n".join(ans))