#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define rep(i, j, k) for (ll i = j; i <= k; ++i)
#define per(i, j, k) for (ll i = j; i >= k; --i)
#define closeSync            \
    ios::sync_with_stdio(0); \
    cin.tie(0);              \
    cout.tie(0)
#define pii pair<ll, ll>
#define fi first
#define se second
const ll INF = 0x3f3f3f3f;
const ll mod = 1e9 + 7;

void solve() {
    int n;
    cin >> n;
    vector<vector<string>> vec(21);
    rep(i, 1, n) {
        string s;
        cin >> s;
        int len = s.length();
        vec[len].push_back(s);
    }
    map<pair<string, string>, int> mp;
    for (int len = 3; len <= 20; ++len) {
        int siz = vec[len].size();
        if (siz < 2) {
            continue;
        }
        for (int i = 0; i < siz; ++i) {
            for (int j = i + 1; j < siz; ++j) {
                vector<int> dif;
                for (int k = 0; k < len; ++k) {
                    if (vec[len][i][k] != vec[len][j][k]) {
                        dif.push_back(k);
                    }
                }
                if (dif.size() == 2 && dif[1] - dif[0] == 1) {
                    string a, b;
                    a += vec[len][i][dif[0]];
                    a += vec[len][i][dif[1]];
                    b += vec[len][j][dif[0]];
                    b += vec[len][j][dif[1]];
                    mp[make_pair(a, b)]++;
                    mp[make_pair(b, a)]++;
                } else if (dif.size() == 1) {
                    int pos = dif[0];
                    if (pos != 0) {
                        string a, b;
                        a += vec[len][i][pos - 1];
                        a += vec[len][i][pos];
                        b += vec[len][j][pos - 1];
                        b += vec[len][j][pos];
                        mp[make_pair(a, b)]++;
                        mp[make_pair(b, a)]++;
                    }
                    if (pos != len - 1) {
                        string a, b;
                        a += vec[len][i][pos];
                        a += vec[len][i][pos + 1];
                        b += vec[len][j][pos];
                        b += vec[len][j][pos + 1];
                        mp[make_pair(a, b)]++;
                        mp[make_pair(b, a)]++;
                    }
                }
            }
        }
    }
    int ans = 0;
    for (auto it : mp) {
        if (it.second == 1)
            ans++;
    }
    cout << ans / 2;
}

int main() {
    closeSync;
    // int T;cin>>T;while(T--)
    solve();
    return 0;
}