#include <bits/stdc++.h> using namespace std; typedef long long ll; int n, i, x, y, dp[2001][2001][2], oo, c, g1, g2, th, l; vector<int> adj[2001]; bool dd[2001][2001]; void dfs(int x, int tr, int khac) { int y, j; for (j = 0; j < adj[x].size(); ++j) { y = adj[x][j]; if (y != khac && y != tr) { dfs(y, x, khac); dp[c][x][1] = max(dp[c][x][1], max(dp[c][x][0] + dp[c][y][0] + 1, dp[c][y][1])); dp[c][x][0] = max(dp[c][x][0], dp[c][y][0] + 1); } } } int main() { ios_base::sync_with_stdio(false), cin.tie(NULL); #ifndef ONLINE_JUDGE freopen("test.inp", "r", stdin); freopen("test.out", "w", stdout); #endif cin >> n; for (i = 1; i < n; ++i) { cin >> x >> y; adj[x].push_back(y); adj[y].push_back(x); } for (i = 1; i <= n; ++i) for (l = 0; l < adj[i].size(); ++l) if (!dd[i][adj[i][l]]) { g1 = i; g2 = adj[i][l]; dd[g1][g2] = dd[g2][g1] = true; ++c; th = 0; dfs(g1, 0, g2); th = 1; dfs(g2, 0, g1); g1 = dp[c][g1][1]; g2 = dp[c][g2][1]; if (g1 && g2) oo = max(oo, g1 * g2); } // cout << dp[3][2][1] << " " << dp[3][4][1] << " "; cout << oo; return 0; }