#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;

#define f0rn(i, a, b) for (int i=a; i<(b); i++)
#define forn(i,n) for(int i = 0; i < n; i++)

#define mp make_pair
#define pb push_back
#define ff first
#define ss second

const int MOD = 1000000007;

vector< pair<string, string> > arr;

int main() {
	ifstream fin("citystate.in");
	ofstream fout("citystate.out");
	int n; fin >> n;
	forn(i,n) {
	    string a, b; fin >> a >> b;
	    arr.pb(mp(a.substr(0,2),b));
	}
	fin.close();
	sort(arr.begin(),arr.end());
	string search[n];
	for(int i = 0; i < n; i++) {
	    search[i] = arr[i].first;
	}
	int cnt = 0;
	for(int i = 0; i < n; i++) {
	    int ind = lower_bound(search,search+n,arr[i].second)-search;
	    if(ind != n) {
	        if(arr[ind].second == arr[i].first) {
	            //cout << arr[ind].first << " " << arr[ind].second;
	            cnt++;
	        }
	    }
	    int t1 = ind+1;
	    while(t1 < n) {
	        if(arr[t1].second == arr[i].first && arr[t1].first == arr[i].second) {
	            //cout << arr[t1].first << " " << arr[t1].second << endl;
	            cnt++;
	        }
	        t1++;
	    }
	    while(ind >= 0) {
	        if(arr[ind].second == arr[i].first && arr[ind].first == arr[ind].second) {
	            //cout << arr[ind].first << " " << arr[ind].second << endl;
	            cnt++;
	        }
	        ind--;
	    }
	}
	fout << cnt/2;
	fout.close();
	return 0;
}