#include <bits/stdc++.h>
using namespace std;
#define maxarray 100005
#define int long long
#define el "\n"
#define vtmc ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define snpos string::npos

bool comp(string s1, string s2) {
    return (s1.length() <= s2.length());
}

bool endsWith(const string& full, const string& suffix) {
    if (suffix.size() > full.size()) return false;
    return full.compare(full.size() - suffix.size(), suffix.size(), suffix) == 0;
}

void solve() {
    int n;
    cin>>n;
    vector<string> v(n);
    for(string& s : v) {
        cin>>s;
    }
    sort(v.begin(),v.end(),comp);
    for(int i=1; i<n; i++) {
        if(!endsWith(v[i],v[0])){
            cout<<"Not found";
            return;
        }
    }
    cout << v[0];
}
signed main() {
    vtmc
    int t=1;
//    cin>>t;
    while(t-->0) {
        solve();
    }
}