#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <map>
#include <set>
#include <climits>
#include <cmath>
#include <fstream>
#include <queue>
#include <stack>
#include <bitset>
using namespace std;
#define ll long long
//cin.tie(0);ios_base::sync_with_stdio(0);
const int MAXN = 5005;
int n;
vector<int> adjList[MAXN];
int cur = 0, cnt = 0;
void bfs(int src) {
int dist[MAXN];
for (int i = 0; i < MAXN; i++) {
dist[i] = INT_MAX;
}
queue<int> q;
q.push(src);
dist[src] = 0;
while (q.size() > 0) {
int cn = q.front();
q.pop();
for (auto i : adjList[cn]) {
if (dist[i] >= dist[cn] + 1) {
q.push(i);
dist[i] = dist[cn] + 1;
if (cur == dist[i]) {
cnt++;
}
else if (cur < dist[i]) {
cur = dist[i];
cnt = 1;
}
}
}
}
}
int main() {
cin >> n;
for (int i = 0; i < n; i++) {
int a, b;
cin >> a >> b;
a--;
b--;
adjList[a].push_back(b);
adjList[b].push_back(a);
}
int ans = 0, best = 0;
for (int i = 0; i < n; i++) {
cur = 0;
cnt = 0;
bfs(i);
if (cur == ans) {
best += cnt;
}
else if (cur > ans) {
ans = cur;
best = cnt;
}
}
cout << best/2 << endl;
}
