#include <bits/stdc++.h>
using namespace std;
string sb[30];
char maxnum = '0';
int n;
size_t maxsize = 0,a;
int length = 0;
int main(){
    cin >> n;
    for(int i = 0; i < n; i++){
        cin >> sb[i];
        maxsize = max(sb[i].size(), maxsize);
    }
    for(int i = 0; i < maxsize; i++){
        maxnum = '0';
        for(int j = 0; j < n; j++){
            if(i < sb[j].size()){
                a = maxnum;
                maxnum = max(maxnum, sb[j][i]);
                length = j;
            }
        }
        cout << sb[length];
    }
    return 0;
}