#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
const double inf = 1e18;
void solve()
{
    int n;
    cin >> n;
    vector<string> a(n);
    for (int i = 0; i < n; i++)
    {
        cin >> a[i];
    }
    map<string, int> ans;
    for (int i = 0; i < n; i++)
    {
        for (int j = i + 1; j < n; j++)
        {
            if (a[i].size() == a[j].size())
            {
                int pos = 1;
                int cnt = 0;
                for (int k = 1; k < a[i].size(); k++)
                {
                    if (a[i][k] != a[j][k] && a[i][k - 1] != a[j][k - 1])
                    {
                        cnt++;
                        pos = k;
                    }
                }
                if (cnt == 1)
                {
                    string s, t;
                    s.push_back(a[i][pos - 1]), s.push_back(a[i][pos]);
                    t.push_back(a[j][pos - 1]), t.push_back(a[j][pos]);
                    if (s > t)
                    {
                        swap(s, t);
                    }
                    s += t;
                    ans[s]++;
                }
            }
        }
    }
    int cnt = 0;
    for (auto it : ans)
    {
        if (it.second == 1)
        {
            cnt++;
        }
    }
    cout << cnt;
    return;
}

signed main()
{
    cin.tie(nullptr)->sync_with_stdio(NULL);

    int t = 1;
    // cin >> t;
    while (t--)
        solve();
    return 0;
}