/*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<string, 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[z]++;
					Map[x]++;
				}
			}
		}
		for(auto h:Map) if(h.second==1) ++ans;




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