/*input
5
CELL
GULL
GUSH
HALL
HASH
*/
#include <bits/stdc++.h>

using namespace std;
const int N = 2000;
string s[N];
int main() {
	cin.tie(0)->sync_with_stdio(0);
	int n;
	cin >> n;
	for (int i = 1; i <= n; ++i)
		cin >> s[i];

	map<string, int> Map;
	for (int i = 1; i < n; ++i)
	{
		for (int r = i + 1; r <= n; ++r)
		{
			if (s[i].size() != s[r].size()) continue;
			int m = s[i].size() - 1;
			string Dif = "", _Dif = "";
			int D = 0;
			for (int j = 0; j < m; ++j)
			{
				if (s[i][j] != s[r][j] && s[i][j + 1] != s[r][j + 1])
				{
					++D;
					if (D == 1)
					{
						Dif = s[i].substr(j, 2) + s[r].substr(j, 2);
						_Dif = s[r].substr(j, 2) + s[i].substr(j, 2);
						//	cout << Dif << '\n';
					}
					else
						break;
				}
			}
			if (D == 1)
			{
				++Map[Dif];
				++Map[_Dif];
			}
		}
	}
	int ans = 0;
	for (auto h : Map) if (h.second == 1) ++ans;
	cout << ans/2;
	return 0;
}