#include <iostream>
#include <string>
#include <map>
using namespace std;

int main(int argc, char* argv[]){
    string str;
    getline(cin, str);
    multimap<char, int> dic;
    for(int i = 0; i < str.size(); ++i){
        if(str[i] >= 'a' && str[i] <= 'z'){
            dic.insert(make_pair(str[i], 1));
        }
        if(str[i] >= 'A' && str[i] <= 'Z'){
            dic.insert(make_pair(tolower(str[i]), 2));
        }
    }
    auto iter = dic.begin();
    for(int i = 0; i < str.size(); ++i){
        if(str[i] >= 'a' && str[i] <= 'z' || str[i] >= 'A' && str[i] <= 'Z'){
            if(iter->second == 1){
                cout << iter->first;
            }
            if(iter->second == 2){
                cout << (char)toupper(iter->first);
            }
            ++iter;
        }
        else{
            cout << str[i];
        }
    }
    cout << endl;

    return 0;
}