/*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];
	int ans = 0;

	map<pair<string,int>, int> Map;

	for (int j = 0; j < 19; ++j)
	{
		Map.clear();
		for (int i = 1; i <= n; ++i)
		{
			for (int p = i + 1; p <= n; ++p)
			{
				if (s[i].size() - 1 < j + 1) continue;
				if (s[i].size() != s[p].size()) continue;
				int Dif = 0;
				for (int o = 0; o < s[i].size(); ++o) if (s[i][o] != s[p][o]) ++Dif;
				if (Dif != 2) continue;
				if (s[i][j] != s[p][j] && s[i][j + 1] != s[p][j + 1])
				{
					string z = "", x = "";
					z = z + s[i].substr(j, 2) + s[p].substr(j, 2);
					x = x + s[p].substr(j, 2) + s[i].substr(j, 2);
					Map[make_pair(z,s[i].size())]++;
					Map[make_pair(x,s[i].size())]++;
				}
			}
		}
		for (auto h : Map) if (h.second == 1) ++ans;




	}
	cout << ans / 2 << '\n';
	return 0;
}