#include<bits/stdc++.h>
using namespace std;
#define el '\n'
const int N = 25005;
const int ALPHA_BET = 26;
const int inf = 2e9;
template<class T> bool ckmax(T& a, const T&b) {
return a < b ? a = b, 1 : 0;
}
int n;
struct Node {
Node*child[ALPHA_BET];
int exits;
Node() {
for(int i = 0 ; i < ALPHA_BET ; i++) {
child[i] = nullptr;
}
exits = 0;
}
};
map<Node* , int> depth;
int cur = 0;
Node *root;
void addString(string s) {
Node *p = root;
for(char f : s) {
int c = f - 'a';
if(p->child[c] == nullptr) {
p->child[c] = new Node();
}
p = p->child[c];
}
p->exits++;
}
void dfs(Node *p) {
depth[p] = 1;
for(int i = 0 ; i < ALPHA_BET ; i++){
if(p->child[i]){
dfs(p->child[i]);
ckmax(depth[p] , depth[p->child[i]] + 1);
// cout << depth[p] << ' ' << char(i + 'a') << el;
}
}
}
string ret;
void solve(Node *p) {
if(p->exits > 0){
ret += 'P';
}
for(int i = 0 ; i < ALPHA_BET ; i++){
if(p->child[i] && depth[p] > depth[p->child[i]] + 1){
ret += (char)(i + 'a');
solve(p->child[i]);
// cout << 1 << ' ' << ret << el;
}
}
for(int i = 0 ; i < ALPHA_BET ; i++){
if(p->child[i] && depth[p] == depth[p->child[i]] + 1){
ret += (char)(i + 'a');
solve(p->child[i]);
// cout << 2 << ' ' << char(i + 'a') << el;
}
}
ret += '-';
}
void GOTO_OLP2025() {
root = new Node();
cin >> n;
for(int i = 0 ; i < n ; i++) {
string s ;
cin >> s;
addString(s);
}
dfs(root);
solve(root);
for(int i = ret.size() - 1 ; i >= 0 ; i--){
if(ret[i] == '-') ret.pop_back();
else break;
}
cout << ret.size() << el;
for(char c : ret) cout << c << el;
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(0) , cout.tie(0);
// freopen("Task.in", "r", stdin);
GOTO_OLP2025();
}
