Language: C++

#include <bits/stdc++.h>
using namespace std;
/*
#if __has_include(<boost/multiprecision/cpp_int.hpp>)
	#include <boost/multiprecision/cpp_int.hpp>
	#include <boost/multiprecision/cpp_dec_float.hpp>
	using bll = boost::multiprecision::cpp_int;
	using bdouble = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<100>>;
	using namespace boost::multiprecision;
#endif
*/
#ifdef LOCAL_TEST
	#define BOOST_STACKTRACE_USE_ADDR2LINE
	#define BOOST_STACKTRACE_ADDR2LINE_LOCATION /usr/local/opt/binutils/bin/addr2line
	#define _GNU_SOURCE 1
	#include <boost/stacktrace.hpp>
	namespace std {
		template<typename T> class dvector : public std::vector<T> {
		public:
			dvector() : std::vector<T>() {}
			explicit dvector(size_t n, const T& value = T()) : std::vector<T>(n, value) {}
			dvector(const std::vector<T>& v) : std::vector<T>(v) {}
			dvector(const std::initializer_list<T> il) : std::vector<T>(il) {}
			dvector(const std::string::iterator first, const std::string::iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::iterator first, const typename std::vector<T>::iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::reverse_iterator first, const typename std::vector<T>::reverse_iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::const_iterator first, const typename std::vector<T>::const_iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::const_reverse_iterator first, const typename std::vector<T>::const_reverse_iterator last) : std::vector<T>(first, last) {}
			T& operator[](size_t n) {
				try { return this->at(n); } catch (const std::exception& e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; return this->at(n); }
			}
			const T& operator[](size_t n) const {
				try { return this->at(n); } catch (const std::exception& e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; return this->at(n); }
			}
		};
	}
	class dbool {
	private:
		bool boolvalue;
	public:
		dbool() : boolvalue(false) {}
		dbool(bool b) : boolvalue(b) {}
		operator bool&() { return boolvalue; }
		operator const bool&() const { return boolvalue; }
	};
	#define vector dvector
	#define bool dbool
	class SIGFPE_exception : std::exception {};
	class SIGSEGV_exception : std::exception {};
	void catch_SIGFPE([[maybe_unused]] int e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; throw SIGFPE_exception(); }
	void catch_SIGSEGV([[maybe_unused]] int e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; throw SIGSEGV_exception(); }
	signed convertedmain();
	signed main() { signal(SIGFPE, catch_SIGFPE); signal(SIGSEGV, catch_SIGSEGV); return convertedmain(); }
	#define main() convertedmain()
#endif
#ifdef LOCAL_DEV
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::vector<T>& v) {
		for (size_t i = 0; i < v.size(); ++i){ s << v[i]; if (i < v.size() - 1) s << "\t"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::vector<std::vector<T>>& vv) {
		s << "\\\n"; for (size_t i = 0; i < vv.size(); ++i){ s << vv[i] << "\n"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::deque<T>& v) {
		for (size_t i = 0; i < v.size(); ++i){ s << v[i]; if (i < v.size() - 1) s << "\t"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::set<T>& se) {
		s << "{ "; for (auto itr = se.begin(); itr != se.end(); ++itr){ s << (*itr) << "\t"; } s << "}"; return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::multiset<T>& se) {
		s << "{ "; for (auto itr = se.begin(); itr != se.end(); ++itr){ s << (*itr) << "\t"; } s << "}"; return s; }
	template <typename T, size_t N> std::ostream& operator<<(std::ostream& s, const std::array<T, N>& a) {
		s << "{ "; for (size_t i = 0; i < N; ++i){ s << a[i] << "\t"; } s << "}"; return s; }
	template<typename T1, typename T2> std::ostream& operator<<(std::ostream& s, const std::map<T1, T2>& m) {
		s << "{\n"; for (auto itr = m.begin(); itr != m.end(); ++itr){ s << "\t" << (*itr).first << " : " << (*itr).second << "\n"; } s << "}"; return s; }
	template<typename T1, typename T2> std::ostream& operator<<(std::ostream& s, const std::pair<T1, T2>& p) {
		return s << "(" << p.first << ", " << p.second << ")"; }
	void debug_impl() { std::cerr << '\n'; }
	template<typename Head, typename... Tail> void debug_impl(Head head, Tail... tail) { std::cerr << " " << head << (sizeof...(tail) ? "," : ""); debug_impl(tail...); }
	#define debug(...) do { std::cerr << "(" << #__VA_ARGS__ << ") ="; debug_impl(__VA_ARGS__); } while (false)
#else
	#define debug(...) do {} while (false)
#endif
//#define int long long
using ll = long long;
//constexpr int INF = (ll)1e9 + 7;//INT_MAX=(1<<31)-1=2147483647
constexpr ll INF = (ll)1e18;//(1LL<<63)-1=9223372036854775807
constexpr ll MOD = (ll)1e9 + 7;
constexpr double EPS = 1e-9;
constexpr ll dx[4] = {1, 0, -1, 0};
constexpr ll dy[4] = {0, 1, 0, -1};
constexpr ll dx8[8] = {1, 0, -1, 0, 1, 1, -1, -1};
constexpr ll dy8[8] = {0, 1, 0, -1, 1, -1, 1, -1};
#define rep(i, n)   for(ll i=0, i##_length=(n); i< i##_length; ++i)
#define repeq(i, n) for(ll i=1, i##_length=(n); i<=i##_length; ++i)
#define rrep(i, n)   for(ll i=(n)-1; i>=0; --i)
#define rrepeq(i, n) for(ll i=(n)  ; i>=1; --i)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
void p() { std::cout << '\n'; }
template<typename Head, typename... Tail> void p(Head head, Tail... tail) { std::cout << head << (sizeof...(tail) ? " " : ""); p(tail...); }
template<typename T> inline void pv(std::vector<T>& v) { for(ll i=0, N=v.size(); i<N; i++) std::cout << v[i] << " \n"[i==N-1]; }
template<typename T> inline bool chmax(T& a, T b) { return a < b && (a = b, true); }
template<typename T> inline bool chmin(T& a, T b) { return a > b && (a = b, true); }
template<typename T> inline void uniq(std::vector<T>& v) { v.erase(std::unique(v.begin(), v.end()), v.end()); }

/*-----8<-----template-----8<-----*/

template< ll char_size >
class TrieNode {
public:
	ll nxt[char_size];

	ll exist;
	vector< ll > accept;

	TrieNode() : exist(0) {
		memset(nxt, -1, sizeof(nxt));
	}
};

/*
あるノードの配下の全てのノードには自身に対応する文字列に共通するプレフィックスがあり, 
ルートには空の文字列が対応している。

計算量：
　add O(|S|)
　query O(|S|)

exist は子供以下に追加された文字列の個数, 
accept はそのノードにマッチする全ての追加された文字列の番号が格納される。

Trie< char_size, margin >(): 
　文字列の種類数 char_size, 開始文字が margin のトライ木を作成する。
add(S): 文字列 S をトライ木に追加する
query(S, f): 文字列 S のプレフィックスに一致する文字列を検索する。
　一致した文字列ごとに関数 f が呼び出される。
size(): ノード数を返す
count(): 存在する文字列の個数を返す
*/

template< ll char_size >
class TrieNode {
public:
	ll nxt[char_size];

	ll exist;
	vector< ll > accept;

	TrieNode() : exist(0) {
		memset(nxt, -1, sizeof(nxt));
	}
};
template< ll char_size, ll margin >
class Trie {
public:
	using Node = TrieNode< char_size >;

	vector< Node > nodes;
	ll root;

	Trie() : root(0) {
		nodes.push_back(Node());
	}

	void update_direct(ll node, ll id) {
		nodes[node].accept.push_back(id);
	}

	void update_child(ll node) {
		++nodes[node].exist;
	}

	void add(const string &str, ll id) {
		ll node_index = 0;
		for(ll str_index = 0; str_index < (ll)str.size(); ++str_index){
			const ll c = str[str_index] - margin;
			if(nodes[node_index].nxt[c] == -1) {
				nodes[node_index].nxt[c] = (ll) nodes.size();
				nodes.push_back(Node());
			}
			update_child(node_index);
			node_index = nodes[node_index].nxt[c];
		}
		update_direct(node_index, id);
	}

	void add(const string &str) {
		add(str, nodes[0].exist);
	}

	template<typename F> void query(const string &str, const F &f, ll str_index = 0) {
		ll node_index = 0;
		for(; str_index <= (ll)str.size(); ++str_index){
			for(auto&& idx : nodes[node_index].accept) f(idx);
			if(str_index == (ll)str.size())break;
			const ll c = str[str_index] - margin;
			if(nodes[node_index].nxt[c] == -1) break;
			node_index = nodes[node_index].nxt[c];
		}
	}

	ll count() const {
		return (nodes[0].exist);
	}

	size_t size() const {
		return nodes.size();
	}
};


/*-----8<-----library-----8<-----*/

void solve() {
	
	ll N;
	cin>>N;
	vector<string> a(N);
	rep(i,N){
		cin>>a[i];
		reverse(all(a[i]));
	}

	sort(a.begin(), a.end(), [](const string &x, const string &y) {
		return x.size() > y.size();
	});

	vector<vector<ll>> pos(N,vector<ll>(26,-INF));
	rep(i,N){
		rep(j,a[i].size())chmax(pos[i][a[i][j]-'a'],j);
	}

	Trie< 26, 'a' > trie;
	rep(i,N){
		if(a[i].size()==(size_t)1)continue;
		string t=a[i].substr(0,a[i].size()-1);
		trie.add(t);
	}

	ll ans=0;
	rep(i,N){
		if(a[i].size()==(size_t)1)continue;
		//index = trie木に追加した単語のindex
		auto update = [&](ll index){
			debug(i,index);
			if(index==i)return;
			ll x=a[index].back()-'a';
			if(pos[i][x]>=(ll)(a[index].size())-1)ans++;
		};
		//Sのi文字目から一致する単語それぞれに対して関数 update が呼ばれる
		debug(a[i]);
		trie.query(a[i], update, 0);
	}
	debug(ans);

	vector<ll> c(26,0);
	rep(i,N){
		if(a[i].size()!=(size_t)1)continue;
		c[a[i][0]-'a']++;
	}
	rep(i,N){
		if(a[i].size()==(size_t)1)continue;
		vector<ll> t(26,false);
		rep(j,a[i].size())t[a[i][j]-'a']=true;
		rep(j,26){
			if(t[j])ans+=c[j];
		}
	}
	p(ans);
}

signed main() {
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);
	//ll Q; cin >> Q; while(Q--)solve();
	solve();
	return 0;
}


Compiler output:
a.cc:138:7: error: redefinition of 'class TrieNode<char_size>'
  138 | class TrieNode {
      |       ^~~~~~~~
a.cc:105:7: note: previous definition of 'class TrieNode<char_size>'
  105 | class TrieNode {
      |       ^~~~~~~~