#include<bits/stdc++.h>
//#define int long long
#define ll long long
#define endl '\n'
#define PII pair<int,int>
using namespace std;
const int maxn = 1e5;
vector<vector<string> > t(25, vector<string>());
int main() {
	ios::sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
	//cout << fixed << setprecision(2);
	int n; cin >> n;
	for (int i = 0; i < n; ++i) {
		string s; cin >> s;
		t[s.size()].push_back(s);
	}
	int ans = 0;
	for (int i = 3; i <= 20; ++i) {
		map<pair<string,int>, int> m;
		for (int j = 0; j < t[i].size(); ++j) {
			for (int k = j + 1; k < t[i].size(); ++k) {
				int p1 = -1, p2 = -1;
				bool flag = false;
				for (int pos = 0; pos < i; ++pos) {
					if (t[i][j][pos] != t[i][k][pos]) {
						if (p1 == -1) p1 = pos;
						else if (p2 == -1) p2 = pos;
						else {
							flag = true;
							break;
						}
					}
				}
				if (flag) continue;
				else {
					m[{t[i][j].substr(p1, 2) + t[i][k].substr(p1, 2), p1}]++;
					m[{t[i][k].substr(p1, 2) + t[i][j].substr(p1, 2), p1}]++;
				}
			}
		}
		for (auto p : m) {
			if (p.second == 1) {
				ans++;
			}
		}
	}
	cout << ans / 2 << endl;
	return 0;
}