#include<iostream>
#include<iomanip>
#include<vector>
#include<math.h>
#include<algorithm>
#include<map>
#include<queue>
#include<stack>
#include<deque>
#include<set>
#include<cmath>
#include<ctime>
#include<bitset>
#define rep(i,a,b) for(int i=a;i<=b;i++)
using namespace std;
using ll = long long;
using vec = vector<ll>;
using Graph = vector<vec>;
using Pair = pair<ll,ll>;

void debug1(vec v){
    for(auto x:v)cout << x << ' ';
    cout << endl;
}
void debug2(vector<Pair> v){
    for(auto x:v)cout << '(' << x.first << ',' << x.second << ')' << endl;
}
void debug3(Graph v){
    rep(i,0,v.size()-1)debug1(v[i]);
    cout << endl;
}
int main(){
    
    set<string>s;
    ll n;
    cin >> n;
    vector<string>a(n+1);
    rep(i,1,n){
        cin >> a[i];
    }
    rep(i,1,n)rep(j,1,n){
        if(i == j)continue;
        s.insert(a[i] + a[j]);
    }
    cout << s.size();
}