ForLiao

#include <string>
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

bool sorter(string a, string b){
    for(int i = 0; i < min(a.size(),b.size()); i++){
        if(a[i] != b[i]) {
            return a[i] > b[i];
        }
    }

    if( a.size() == b.size()){
        return false;
    } else if (a.size() < b.size()) {
        return sorter( a , b.substr( a.size() ,b.size() - a.size() ) );
    } else {
        return sorter( a.substr(b.size() , a.size()-b.size()) , b );
    }
}

int main(){
    vector<string> fragements;
    string s = "start";

    while(s!=""){
        getline(cin,s);
        if(s!=""){
            fragements.emplace_back(s);
        }
    }

    if(fragements.size() == 1){
        cout << fragements[0];
    } else {
        sort(fragements.begin(), fragements.end(),  sorter);

        for (auto & i : fragements) {
            cout << i;
        }
    }

}