while True:
try:
str_ = input()
dict_ = {}
res = ''
for s in str_:
if s not in dict_.keys():
dict_[s] = 1
else:
dict_[s] += 1
min_ = min(dict_.values())
for s in str_:
if dict_[s] != min_:
res += s
print(res)
except:
break