#include <bits/stdc++.h>
#define file ""
#define all(x) x.begin(), x.end()
#define sc second
#define fr first
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const ll inf = 1e18 + 5;
const ll mod = 1e9 + 7;
const int N = 6e5 + 5;
int dx[] = {+1, 0, -1, 0};
int dy[] = {0, +1, 0, -1};
int n, mx;
vector<int> g[N], ans(N);
void go(int x) {
vector<int> dp(n + 1, 1e9), cnt(n + 1);
cnt[x] = 1;
dp[x] = 0;
queue<int> q;
q.push(x);
while (!q.empty()) {
int v = q.front();
q.pop();
for (int to : g[v]) {
if (dp[to] == dp[v] + 1) {
cnt[to] += cnt[v];
continue;
}
if (dp[to] > dp[v] + 1) {
cnt[to] = cnt[v];
dp[to] = dp[v] + 1;
q.push(to);
}
}
}
//cerr << x << "\n";
for (int i = 1; i <= n; i++) {
//cerr << i << " " << dp[i] << " " << cnt[i] << endl;
ans[dp[i]] += cnt[i];
mx = max(mx, dp[i]);
}
cerr << endl;
}
int main() {
ios_base :: sync_with_stdio(false);
cin.tie(nullptr);
srand(time(nullptr));
cin >> n;
for (int i = 1; i <= n; i++) {
int x, y;
cin >> x >> y;
g[x].pb(y);
g[y].pb(x);
}
for (int i = 1; i <= n; i++) {
go(i);
}
cout << ans[mx] / 2;
return 0;
}
