#include<iostream>
#include<vector>
#include<algorithm>
#include<vector>
#include<cmath>
#include<string>
#include<cstring>
#include<queue>
#include<map>
using namespace std;
int n;
char s[2000][30];
map<pair<string,string> ,int>m;
int c[1000010];
int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf("%s",s[i]+1);
    }
    //m.clear();
    int tot=0;
    for(int i=1;i<=n;i++)
    for(int j=i+1;j<=n;j++)
    {
        int len1=strlen(s[i]+1);
        int len2=strlen(s[j]+1);
        if(len1!=len2)continue;
        int cnt=0,pos;
        for(int k=1;k<len1;k++){
            if((s[i][k]!=s[j][k])&&(s[i][k+1]!=s[j][k+1])){
                cnt++;pos=k;
            }
        }
        if(cnt!=1)continue;
        string a,b;
        a.push_back(s[i][pos]);a.push_back(s[i][pos+1]);
        b.push_back(s[j][pos]);b.push_back(s[j][pos+1]);
        if(s[i][pos]>s[j][pos])swap(a,b);
        int sum=a[0]-'A';
        sum*=26;
        sum+=a[1]-'A';
        sum*=26;
        sum+=b[0]-'A';
        sum*=26;
        sum+=b[1]-'A';
        c[sum]++;
        tot=max(sum,tot);
    }
    int ans=0;
    for(int i=1;i<=tot;i++){
        if(c[i]==1)ans++;
    }
    cout<<ans;
    return 0;
}