#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
#define FOR(i,a,n) for(int i=a;i<(int)(n);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(a) (a).begin(),(a).end()
#define MP(a,b) make_pair(a,b)
#define PB(a) push_back(a)
#define F first
#define S second
const int INF = 2000000000;
const int DX[4]={0,1,0,-1}, DY[4]={-1,0,1,0};
struct P{int x;int y;P(int X=0,int Y=0){x=X;y=Y;}};

int main() {
    int N;
    cin >> N;
    vector<pair<char,string> > s(N);
    REP(i,N) {
        string str;
        cin >> str;
        s[i] = MP(str[0],str);
        s[i].S.erase(s[i].S.begin());
    }
    sort(ALL(s));

    string T="";
    int i=0;
    while(true) {
        T += s[0].F;
        if(!s[0].S.empty()) {
            s[0].F = s[0].S[0];
            s[0].S.erase(s[0].S.begin());
        }
        else s[0].F = '|';
        if(s[0].F == '|') {
            i++;
            if(i==N) break;
        }
        sort(ALL(s));
    }
    cout << T << endl;
    return 0;
}