ABC 353

struct Trie {
    vector<map<char, int>> to;
    vll cnt;

    Trie()
        : to(1), cnt(1) {};

    int add(string s) {
        int v = 0;
        for (char c : s) {
            if (to[v].count(c) == 0) {
                int u = to.size();
                to.push_back(map<char, int>());
                to[v][c] = u;
                cnt.push_back(0);
            }
            v = to[v][c];
            cnt[v]++;
        }
        return v;
    }
};

void solve() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N;
    cin >> N;
    vector<string> S(N);
    rep(i, N) cin >> S[i];

    Trie trie;

    for (string s : S)
        trie.add(s);

    ll ans = 0;
    for (ll x : trie.cnt) {
        ans += x * (x - 1) / 2;
    }
    cout << ans << endl;
}