include

include

include

using namespace std; int n,m;

define N 100005

int fir[N],to[2*N],nxt[2*N],cd[2*N],cnt; void adde(int a,int b,int c) {

to[++cnt]=b;nxt[cnt]=fir[a];fir[a]=cnt;cd[cnt]=c;
to[++cnt]=a;nxt[cnt]=fir[b];fir[b]=cnt;cd[cnt]=c;

}

define LL long long

int cir[N],D[N],fa[N],dep[N]; bool vis[N]; void findcir(int u) {

dep[u]=dep[fa[u]]+1;
int v,p;
for(p=fir[u];p;p=nxt[p]){
	v=to[p];
	if(v==fa[u]) continue;
	if(!dep[v]){fa[v]=u;findcir(v);}
	else if(dep[v]<dep[u]){
		for(int j=u;;j=fa[j]){
			vis[j]=1;cir[++m]=j;
			if(j==v)break;
		}
	}
}

} LL hei[N],ans; void dfs(int u,int f)//这个地方之前写错了，计算子树直径时不应该沿用第一次的父亲 {

int v,p,w;
for(p=fir[u];p;p=nxt[p]){
	v=to[p];w=cd[p];
	if(v!=f&&!vis[v]){
		dfs(v,u);
		ans=max(hei[u]+hei[v]+w,ans);
		hei[u]=max(hei[u],hei[v]+w);
	}
}

} LL g1[N],g2[N],h1[N],h2[N]; int main() {

int n,i,u,v,w,p;
scanf("%d",&n);
for(i=1;i<=n;i++){
	scanf("%d%d%d",&u,&v,&w);
	adde(u,v,w);
}
findcir(1);
for(i=1;i<=n;i++)
	if(vis[i]) dfs(i,0);
cir[m+1]=cir[1];
for(i=1;i<=m;i++)
	for(p=fir[cir[i]];p;p=nxt[p])
		if(to[p]==cir[i+1]){
			D[i]=cd[p];
			break;
		}
LL sum=0,mx=hei[cir[1]]+D[1];
for(i=2;i<=m;i++){
	sum+=D[i-1];
	h1[i]=max(h1[i-1],hei[cir[i]]+sum);
	g1[i]=max(g1[i-1],hei[cir[i]]+mx);
	mx=max(mx,hei[cir[i]])+D[i];
}
sum=0;mx=hei[cir[1]]+D[m];
for(i=m;i>1;i--){
	sum+=D[i];
	h2[i]=max(h2[i+1],hei[cir[i]]+sum);
	g2[i]=max(g2[i+1],hei[cir[i]]+mx);
	mx=max(mx,hei[cir[i]])+D[i-1];
}
LL ret=1ll<<60;
for(i=1;i<=m;i++)
	ret=min(ret,max(ans,max(h1[i]+h2[i+1],max(g1[i],g2[i+1]))));
printf("%.1f",1.0*ret/2);

}