#include<iostream> #include<map> #include<algorithm> using namespace std; int main(){ string input; cin>>input; map<char, int> word_times; for(auto c: input){ word_times[c]++; } int min_time = word_times[input[0]]; //从输入字符串的首字符开始遍历 for(auto pa: word_times){ min_time = min(min_time, pa.second); } for(auto c:input){ if(word_times[c] > min_time){ cout<<c; } } cout<<endl; return 0; }