#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int n;
	cin >> n;
	vector<string> s(n);
	for (string& si : s)
		cin >> si;
	map<tuple<int, int, string, string>, int> cnt;
	FOR(i, 0, n)
		FOR(j, i + 1, n)
		{
			if (SZ(s[i]) != SZ(s[j]))
				continue;
			int m = SZ(s[i]);
			int p = 0, pos1 = -1, pos2 = -1;
			FOR(k, 0, m)
			{
				if (s[i][k] != s[j][k])
				{
					p++;
					if (pos1 == -1)
						pos1 = k;
					pos2 = k;
				}
			}
			if (p == 2 && pos1 + 1 == pos2)
			{
				string t1 = s[i].substr(pos1, 2);
				string t2 = s[j].substr(pos1, 2);
				if (t1 > t2)
					swap(t1, t2);
				cnt[{m, pos1, t1, t2}]++;
			}
		}
	int ans = 0;
	for (auto [x, c] : cnt)
		if (c == 1)
			ans++;
	cout << ans << "\n";
	return 0;
}