s = input().strip()

# 构造一个字典
freq = {}

# 遍历字符串,若字典中不存在该字符则新增该字符并设置为1,否则在原来基础上自增1
for char in s:
    freq[char] = freq.get(char, 0) + 1

# 找到字典中的最小值,待会要用
min_freq = min(freq.values())

# 把所有字典中最小值对应的字符删除
result = [char for char in s if freq[char] != min_freq]

# 字典转换成字符串输出
print(''.join(result))