#include<iostream> #include<string> #include<vector> using namespace std; int main () { string s; while (getline(cin, s)) { int len = s.size(); string ans; // 创建string类型的向量数组,并逐个把s中的字符按26个字母打进去 vector<string> arr(26); for (int i = 0; i < len; ++i) { arr[s[i] - 'a'].push_back(s[i]); } // 找到字符出现数量不为零的最小值 int minN = 100; for (int i = 0; i < 26; ++i) { if (arr[i].size() != 0 && arr[i].size() < minN) minN = arr[i].size(); } // 把符合要求的字符扔给新字符串并返回 for (int i = 0; i < len; ++i) { if (arr[s[i] - 'a'].size() != 0 && arr[s[i] - 'a'].si***N) ans += s[i]; } cout << ans << endl; } return 0; }