#include<bits/stdc++.h>
using namespace std;
using LL = long long;
using PII = pair<int, int>;
vector<string> alls(1e5 + 10);
map<string, int> mp;

int main()
{
	int n;
	cin >> n;

	for (int i = 1; i <= n; i++) {
		cin >> alls[i];
	}

	for (int i = 1; i <= n; i++) {
		for (int j = i + 1; j <= n; j++) {
			if ((int)alls[i].size() == (int)alls[j].size()) {
				vector<int> tmp;
				for (int k = 0; k < (int)alls[i].size(); k++) {
					if (alls[i][k] != alls[j][k]) {
						tmp.push_back(k);
					}
				}

				if ((int)tmp.size() == 2 && tmp[0] + 1 == tmp[1]) {
					string t1 = alls[i].substr(tmp[0], tmp[1] + 1), t2 = alls[j].substr(tmp[0], tmp[1] + 1);
					if (t1 > t2)
						swap(t1, t2);
					string t = t1 + t2 + to_string(alls[i].size()) + to_string(tmp[0]);
					mp[t]++;
				}
			}
		}
	}

	int ans = 0;
	for (auto [x, y] : mp) {
		if (y == 1)
			ans ++;
	}
	cout << ans << endl;
	return 0;
}