#include<bits/stdc++.h>
using namespace std;
#define i128 __int128
#define ull unsigned long long
#define int long long
#define fo(i,l,r) for(int i=l;i<=r;i++)
#define fd(i,r,l) for(int i=r;i>=l;i--)
#define sqrt __builtin_sqrt
#define pii pair<int,int>
#define pll pair<long long,long long>
#define pdd pair<double,double>
#define tiii tuple<int,int,int>
#define fi first
#define se second
#define mem(a,b) memset(a,b,sizeof a)
inline int read(){char c=getchar();int a=0,b=1;while(c<'0'||c>'9')b=(c=='-'?-1:b),c=getchar();while(c>='0'&&c<='9')a=a*10+(c^48),c=getchar();return a*b;}inline void write(int x){if(x<0)putchar('-'),x=-x;if(x>9)write(x/10);putchar(x%10+'0');}template<typename T>void cmax(T&x,T y){x=max(x,y);}template<typename T>void cmin(T&x,T y){x=min(x,y);}
int n,x,y,L,w[500005],f[500005],ans,maxn,tmp;
int a[500005],b[500005],c[500005],d[500005];
bool flag;
bitset<500005>vis;
vector<pii>v[500005];
int S[500005],sk[500005],Top,top;
void find_r(int x,int fa){
	if(flag)return;
	if(vis[x]){
		while(S[Top]^x)sk[++top]=S[Top--];
		sk[++top]=S[Top--],flag=1;
		return;
	}
	vis[x]=1,S[++Top]=x;
	for(auto[i,j]:v[x])if(i^fa){
		find_r(i,x);
		if(flag)return;
	}
	Top--;
}
void initf(int x,int fa,int dis){
	if(maxn<dis)maxn=dis,tmp=x;
	for(auto[i,j]:v[x])if(i^fa)initf(i,x,dis+j);
}
void initg(int x,int fa,int no1,int no2,int dis){
	cmax(ans,dis);
	for(auto[i,j]:v[x])if(i^fa&&i^no1&&i^no2)initg(i,x,no1,no2,dis+j);
}
int work(int x){
	int dis=0,st=0;
    // fo(i,1,top)cerr<<sk[i]<<' ';
	// cerr<<'\n';
	fo(i,1,top)dis+=w[i-1],a[i]=max(a[i-1],dis+f[sk[i]]),b[i]=max(b[i-1],st+dis+f[sk[i]]),cmax(st,f[sk[i]]-dis);//cerr<<a[i]<<' '<<b[i]<<'\n';;
	dis=st=0;
	fd(i,top,1)dis+=(i<top)*w[i],c[i]=max(c[i+1],dis+f[sk[i]]),d[i]=max(d[i+1],st+dis+f[sk[i]]),cmax(st,f[sk[i]]-dis);//cerr<<c[i]<<' '<<d[i]<<' '<<dis<<'\n';
	int anst=b[top];
	fo(i,2,top)cmin(anst,max({b[i-1],d[i],a[i-1]+w[top]+c[i]}));
	return max(ans,anst);
}
signed main(){
	ios::sync_with_stdio(0);
	// freopen("foodshop.in","r",stdin);
	cin>>n;
	fo(i,1,n)cin>>x>>y>>L,v[x].push_back({y,L}),v[y].push_back({x,L});
	find_r(1,0);
	fo(i,1,top){
		int l=sk[i-1?i-1:top],r=sk[i>=top?1:i+1];
		for(auto[j,k]:v[sk[i]])
			if(j==r)w[i]=k;
			else if(j^l){
				maxn=tmp=0;
				initf(j,sk[i],0),cmax(f[sk[i]],maxn+k);
				initg(tmp,0,l,r,0);
			}
	}
	cout<<fixed<<setprecision(1)<<1.*work(sk[1])/2;
	return 0;
}