x = str(input())
mp = [0 for _ in range(26)]

for c in x:
    c = ord(c) - ord('a')
    mp[c] += 1

mi = int(999)
for i in range(26):
    if mp[i] != 0:
        mi = min(mp[i], mi)

for i in range(26):
    if mp[i] == mi:
        x = x.replace(chr(ord('a')+ i),'')

print(x)

删除最小的数值的元素