#include <bits/stdc++.h>
using namespace std;
const long long N = 5050;
long long n, d[N], cnt[N];
vector<long long> adj[N];
pair<long long, long long> operator+(pair<long long, long long> p1, pair<long long, long long> p2) {
pair<long long, long long> res = {max(p1.first, p2.first), 0};
if (p1.first == res.first) res.second += p1.second;
if (p2.first == res.first) res.second += p2.second;
return res;
}
void bfs(long long st) {
memset(d, 63, sizeof d);
memset(cnt, 0, sizeof cnt);
cnt[st] = 1;
d[st] = 0;
queue<long long> q;
q.push(st);
while (!q.empty()) {
long long u = q.front();
q.pop();
for (long long v: adj[u]) {
if (d[v] > d[u] + 1) {
d[v] = d[u] + 1;
q.push(v);
}
if (d[v] == d[u] + 1)
cnt[v] += cnt[u];
}
}
}
void input() {
cin >> n;
for (long long i = 0, u, v; i < n; i++) {
cin >> u >> v;
u--, v--;
adj[u].push_back(v);
adj[v].push_back(u);
}
}
void solve() {
pair<long long, long long> ans = {-1, 0};
for (long long i = 0; i < n; i++) {
bfs(i);
for (long long j = 0; j < n; j++) {
ans = (ans + make_pair(d[j], cnt[j]));
}
}
cout << ans.second / 2;
}
int main() {
ios:: sync_with_stdio(0), cin.tie(0), cout.tie(0);
input();
solve();
}
