#include<iostream>
#include<vector>
#include<algorithm>
#include<vector>
#include<string>
#include<cstring>
#include<queue>
#include<map>
using namespace std;
#define int long long
#define endl "\n"
map<pair<string,string>,int>idx;
void solve(){
	int n;
	cin>>n;
	vector<string>arr(n+1);
	for(int i=1;i<=n;i++){
		cin>>arr[i];
	}
	for(int i=1;i<=n;i++){
		for(int j=i+1;j<=n;j++){
			// if(arr[i].size()!=arr[j].size())continue;
			{
				int cnt1=0;
				int pos=-1;
				for(int k=0;k<(int)arr[i].size()-1;k++){
					if((arr[i][k]!=arr[j][k])&&(arr[i][k+1]!=arr[j][k+1])){
						cnt1++;
						pos=k;
					}
				}
				if(cnt1!=1)continue;
				pair<string,string>t;
				t.first=arr[i].substr(pos,2);
				t.second=arr[j].substr(pos,2);
				if(t.first>t.second)swap(t.first,t.second);
				idx[{t.first,t.second}]++;
			}
		}
	}
	int ans=0;
	for(auto t:idx){
		if(t.second==1)ans++;
	}
	cout<<ans<<endl;
}

signed main(){
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int t;
	solve();
}