#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
#define FF first
#define SS second
#define PB push_back
#define MP make_pair
int n;
char s[1511][22];
int cnt[21][26][26][26][26];
int solve(vector<string> v) {
	if(v.size()==0) return 0;
	int l = v[0].size();
	memset(cnt, 0, sizeof(cnt));
	for (int i=0; i<v.size(); i++) {
		for (int j=i+1; j<v.size(); j++) {
			vector<int> pos;
			for (int k=0; k<l; k++) {
				if (v[i][k] != v[j][k]) {
					pos.PB(k);
				}
			}
			if (pos.size()==2 && pos[0]+1==pos[1]) {
				int p = pos[0];
				cnt[p][v[i][p]-'A'][v[i][p+1]-'A'][v[j][p]-'A'][v[j][p+1]-'A']++;
			}
		}
	}
	int ans = 0;
	for (int i=0; i<v.size(); i++) {
		for (int j=i+1; j<v.size(); j++) {
			vector<int> pos;
			for (int k=0; k<l; k++) {
				if (v[i][k] != v[j][k]) {
					pos.PB(k);
				}
			}
			if (pos.size()==2 && pos[0]+1==pos[1]) {
				int p = pos[0];
				if (cnt[p][v[i][p]-'A'][v[i][p+1]-'A'][v[j][p]-'A'][v[j][p+1]-'A'] == 1) {
					ans++;
				}
			}
		}
	}
	return ans;
}

vector<string> v[22];

int main() {
	cin>>n;
	for (int i=1; i<=n; i++) {
		string s;
		cin>>s;
		int l = s.size();
		v[l].PB(s);
	}
	int ans = 0;
	for (int i=2; i<=20; i++) {
		ans += solve(v[i]);
	}
	cout<<ans<<endl;
	return 0;
}