1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 #include<iostream>
 5 #include<cmath>
 6 using namespace std;
 7 const int maxd=3010;
 8 typedef long long ll;
 9 struct asd{
10     ll from,to,next;
11 }b[maxd*2];
12 ll head[maxd],tot=1;
13 void ad(ll aa,ll bb){
14     b[tot].from=aa;
15     b[tot].to=bb;
16     b[tot].next=head[aa];
17     head[aa]=tot++;
18 }
19 ll pa[maxd][maxd],f[maxd][maxd],g[maxd][maxd];
20 ll rt=1;
21 void dfs(ll now,ll fa){
22     g[rt][now]=1;
23     for(ll i=head[now];i!=-1;i=b[i].next){
24         ll u=b[i].to;
25         if(u==fa) continue;
26         pa[rt][u]=now;
27         dfs(u,now);
28         g[rt][now]+=g[rt][u];
29     }
30 }
31 ll solve(ll u,ll v){
32     if(u==v) return 0;
33     if(f[u][v]) return f[u][v];
34     return f[u][v]=max(solve(u,pa[u][v]),solve(v,pa[v][u]))+g[u][v]*g[v][u];
35 }
36 int main(){
37     memset(head,-1,sizeof(head));
38     ll n;
39     scanf("%lld",&n);
40     for(ll i=1;i<n;i++){
41         ll aa,bb;
42         scanf("%lld%lld",&aa,&bb);
43         ad(aa,bb);
44         ad(bb,aa);
45     }
46     for(ll i=1;i<=n;i++){
47         rt=i;
48         dfs(i,-1);//递归，预处理s数组和pa数组
49     }
50     ll ans=-1;
51     for(ll i=1;i<=n;i++){
52         for(ll j=1;j<=n;j++){
53             ans=max(solve(i,j),ans);//取最大值
54         }
55     }
56     printf("%lld\n",ans);
57     return 0;
58 }