#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;


template<typename T>
bool isConstains(const vector<T>& v, T t) {
    return find(v.begin(), v.e***.end();
}


int main() {
    
    string str;
    cin >> str;
    
    vector<int> v(26,0);
    
    for(char c : str) {
        int index = c-'a';
        v.at(index)++; 
    }
    
    int max = 26;
    for(int i : v) {
        if(i!=0&&i<max) max = i; 
    }
    vector<char> del;
    for(int i = 0; i < v.size(); i++) {
        if(v.at(i)==max) del.push_back('a'+i);
    }
    for(char c : str) {
        if(!isConstains(del, c)) cout << c;
    }
    cout << endl;
    
    return 0;
}