#include <bits/stdc++.h>
using namespace std;
const int L = 22;
int n;
vector<string> vec[L];
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        static string s;
        cin >> s;
        vec[s.size()].push_back(s);
    }
    int ans = 0;
    for (int i = 3; i <= 20; ++i) {
        sort(vec[i].begin(), vec[i].end());
        vec[i].erase(unique(vec[i].begin(), vec[i].end()), vec[i].end());
        map<string, int> mp[L];
        int k = vec[i].size();
        for (int a = 0; a < k; ++a)
            for (int b = a + 1; b < k; ++b) {
                string &sa = vec[i][a];
                string &sb = vec[i][b];
                int fir = -2, la = -2;
                for (int t = 0; t < i; ++t) if (sa[t] != sb[t]) {
                    if (fir == -2) fir = t;
                    la = t;
                }
                // cout << fir << ' ' << la << endl;
                if (fir + 1 == la) {
                    // cout << fir << ' ' << sa.substr(fir, 2) + sb.substr(fir, 2) << endl;
                    mp[fir][sa.substr(fir, 2) + sb.substr(fir, 2)] += 1;
                }
            }
        for (int t = 0; t <= 20; ++t) 
            for (auto [_, cnt] : mp[t])
                ans += (cnt == 1);
    }
    cout << ans << endl;
    return 0;
}