#include <bits/stdc++.h>
#define int long long
#define x first
#define y second
#define pb push_back
void debug() {std::cerr << "\n";}
template<class T, class... OtherArgs>
void debug(T &&var, OtherArgs &&... args) {
    std::cerr << std::forward<T>(var) << " ";
    debug(std::forward<OtherArgs>(args)...);
}
#define SZ(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef long long LL;
typedef long double LD;
typedef unsigned long long ULL;
typedef pair<int, int> PII;
const int N = 2010, M = 10000010;
const int P = 998244353;
LL powmod(LL a, LL b, LL p = P) {LL res = 1 % p; a %= p; assert(b >= 0); for(; b; b >>= 1) { if (b & 1) res = res * a % p; a = a * a % p; } return res; }

int n, m;

void solve() {
    cin >> n;
    vector<string> s(n);
    for (int i = 0; i < n; i++) {
        cin >> s[i];
    }

    int ans = 0;
    for (int l = 0; l < 18; l++) {
        vector<vector<string>> mp;
        map<string, int> id;
        for (int i = 0; i < n; i++) {
            if (l + 1 >= s[i].size()) continue;
            string t = s[i].substr(0, l) + s[i].substr(l + 2);
            if (!id.count(s[i].substr(l, 2))) mp.pb({}), mp.back().pb(t), id[s[i].substr(l, 2)] = mp.size() - 1;
            else mp[id[s[i].substr(l, 2)]].pb(t);
        }
        for (int i = 0; i < mp.size(); i++) {
            set<string> has;
            for (int j = i + 1; j < mp.size(); j++) {
                for (auto st : mp[j]) {
                    has.insert(st);
                }
                int c = 0;
                for (auto st : mp[i]) {
                    c += has.count(st);
                    if (c > 1) {
                        break;
                    }
                }
                // if (c == 1) debug(l, i, j);
                ans += c == 1;
            }
        }
    }
    cout << ans << '\n';
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(20);
    int _ = 1;
    // cin >> _;
    while (_--) solve();
}