1 #include <cstdio>
2 #include <iostream>
3 #include <cstring>
4 #include <vector>
5 #include <algorithm>
6 using namespace std;
7 const int maxn=1e7+10;
8 int n,cnt,k,bel,tot,head1,tail,boo,head[maxn],dfn[maxn],low[maxn],belong[maxn];
9 bool vis[maxn];
10 int root[maxn],q[maxn*2];
11 long long ans,f[maxn*2],len[maxn*2],pre[maxn*2],dis[maxn*2],mid;
12 struct edge{ int v,to,from; }e[maxn*2];
13 struct node{ int x,y,v; }a[maxn];
14 vector<int>Q;
15 void insert(int a,int b,int c)
16 {
17 e[++cnt].to=b; e[cnt].from=head[a]; e[cnt].v=c; head[a]=cnt;
18 e[++cnt].to=a; e[cnt].from=head[b]; e[cnt].v=c; head[b]=cnt;
19 }
20 void dfs(int x,int fa)
21 {
22 long long max1=0,max2=0,l=0;
23 for (int i=head[x];i;i=e[i].from)
24 if (belong[e[i].to]!=k&&e[i].to!=fa)
25 {
26 dfs(e[i].to,x);
27 l=f[e[i].to]+e[i].v;
28 if (l>max1) max2=max1,max1=l; else max2=max(l,max2);
29 }
30 ans=max(max1+max2,ans);
31 f[x]=max1;
32 }
33 void tarjan(int x,int fa)
34 {
35 dfn[x]=low[x]=++cnt,vis[x]=1;
36 Q.push_back(x);
37 for (int i=head[x];i;i=e[i].from)
38 if (e[i].to!=fa)
39 {
40 if (!dfn[e[i].to])
41 {
42 tarjan(e[i].to,x);
43 low[x]=min(low[x],low[e[i].to]);
44 }
45 else if (vis[e[i].to]) low[x]=min(low[x],dfn[e[i].to]);
46 }
47 if (low[x]==dfn[x])
48 {
49 bel++;
50 int y=0,boo=0;
51 if (Q.back()!=x) boo=1,k=bel;
52 while (y!=x)
53 {
54 y=Q.back(),Q.pop_back();
55 belong[y]=bel,vis[y]=0;
56 if (boo) root[++tot]=y;
57 }
58 }
59 }
60 bool cmp(node a,node b) { return a.x==b.x?(a.y==b.y?a.v<b.v:a.y<b.y):a.x<b.x; }
61 int main()
62 {
63 freopen("darksoul.in","r",stdin),freopen("darksoul.out","w",stdout);
64 scanf("%d",&n);
65 for (int i=1;i<=n;i++)
66 {
67 scanf("%d%d%d",&a[i].x,&a[i].y,&a[i].v);
68 if (a[i].x>a[i].y) swap(a[i].x,a[i].y);
69 }
70 sort(a+1,a+n+1,cmp);
71 bool boo=false;
72 for (int i=1;i<=n;i++)
73 if (a[i].x==a[i].y||a[i].x==a[i-1].x&&a[i].y==a[i-1].y) boo=true;
74 else insert(a[i].x,a[i].y,a[i].v);
75 if (boo)
76 {
77 k=-1,dfs(1,0),printf("%lld",ans+1);
78 return 0;
79 }
80 cnt=0,tarjan(1,0);
81 for (int i=1;i<=tot;i++) dfs(root[i],0),len[i]=f[root[i]];
82 for (int i=1;i<=tot;i++)
83 for (int j=head[root[i]];j;j=e[j].from)
84 if (e[j].to==root[i!=1?i-1:tot])
85 {
86 dis[i]=(long long)e[j].v;
87 break;
88 }
89 for (int i=1;i<=tot;i++) dis[i+tot]=dis[i],len[i+tot]=len[i];
90 for (int i=1;i<=tot*2;i++) pre[i]=pre[i-1]+dis[i];
91 mid=pre[tot];
92 head1=tail=q[head1]=1;
93 for (int i=2;i<=2*tot;i++)
94 {
95 while (head1<=tail&&(pre[i]-pre[q[head1]]>mid/2)) head1++;
96 if (head1<=tail) ans=max(ans,len[q[head1]]+len[i]+pre[i]-pre[q[head1]]);
97 while (head1<=tail&&(len[i]-pre[i]>=len[q[tail]]-pre[q[tail]])) tail--;
98 q[++tail]=i;
99 }
100 printf("%lld",ans+1);
101 }
