#pragma GCC optimize ("O3")
#include <bits/stdc++.h>
#define pii pair<int, int>
#define piii pair<pii, int>
#define vi vector<int>
#define vvi vector<vi>
#define vpii vector<pii>
#define vvpii vector<vpii>
#define f first
#define s second
#define oo 1000000001
#define eb emplace_back
#define pb push_back
#define mpr make_pair
#define size(v) (int)v.size()
#define ln '\n'
#define ull unsigned long long
#define ll long long
#define all(v) v.begin(), v.end()
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
struct Trie {
bool isEnd;
int8_t depth;
unordered_map<char, Trie*>link;
Trie(int8_t dep): isEnd(false), depth(dep) {}
void add(string &s) {
Trie *node = this;
int8_t len = size(s);
for (char c : s) {
if (node->link.find(c) != node->link.end()) {
node = node->link[c];
node->depth = max(node->depth, len);
} else {
node = node->link[c] = new Trie(len);
}
}
node->isEnd = true;
}
string traverse(Trie *node) {
string res = "";
if (node->isEnd) res += 'P';
char imaxDep = '?';
for (char i = 'a'; i <= 'z'; ++i) {
if (node->link.find(i) != node->link.end() && (imaxDep == '?' || node->link[i]->depth > node->link[imaxDep]->depth)) {
imaxDep = i;
}
}
if (imaxDep != '?') {
for (char i = 'a'; i <= 'z'; ++i) {
if (i != imaxDep && node->link.find(i) != node->link.end()) {
res += i;
res += traverse(node->link[i]);
res += '-';
}
}
res += imaxDep;
res += traverse(node->link[imaxDep]);
res += '-';
}
return res;
}
};
void solve() {
int n;
cin >> n;
string s;
Trie *root = new Trie(0);
for (int i = 0; i < n; ++i) {
cin >> s;
root->add(s);
}
string res = root->traverse(root);
while (res.back() == '-') res.pop_back();
cout << size(res) << ln;
for (char c : res) {
cout << c << ln;
}
}
int main() {
ios_base::sync_with_stdio(false);
solve();
return 0;
}
