E. Essay Time

#include <bits/stdc++.h>

#define DIM 8000005
#define ALPHABET_SIZE 'z'-'a'+1

using namespace std;

int TRIE[DIM][ALPHABET_SIZE];
bool used[DIM];
int sz = 1;
vector<string> repeated;

void build();
void add(string s);

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n;
    string s;

    build();
    cin >> n;
    while(n--){
        cin >> s;
        if(s.length()>=4)
            add(s);
    }
    if(repeated.empty()){
        cout << "SAFO\n";
    }else{
        cout << repeated.size() << "\n";
        for(int i=0;i<repeated.size();i++){
            cout << repeated[i] << "\n";
        }
    }

    return 0;
}

void build(){
    for(int i=0;i<DIM;i++){
        used[i] = 0;
        for(int j=0;j<ALPHABET_SIZE;j++){
            TRIE[i][j] = -1;
        }
    }
    return;
}

void add(string s){
    int node = 0;
    for(int i=0;i<s.length();i++){
        if(TRIE[node][s[i]]==-1){
            TRIE[node][s[i]] = sz++;
        }
        node = TRIE[node][s[i]];
    }
    if(used[node]){
        repeated.push_back(s);
    }
    used[node] = 1;
    return;
}