#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<vector>
#include<queue>
using namespace std;
const int SIZEN=100010;
const int INF=0x7fffffff/2;
int N,M;
int S=0;
vector<pair<int,int> > c[SIZEN];
void addedge(int u,int v,int len){
	c[u].push_back(make_pair(v,len));
}
int f[SIZEN]={0};
bool inq[SIZEN];
queue<int> Q;
void SPFA(void){
	memset(inq,0,sizeof(inq));
	for(int i=0;i<=N;i++) f[i]=INF;
	f[S]=0;Q.push(S);inq[S]=true;
	while(!Q.empty()){
		int x=Q.front();Q.pop();inq[x]=false;
		for(int i=0;i<c[x].size();i++){
			int u=c[x][i].first;
			if(f[x]+c[x][i].second<f[u]){
				f[u]=f[x]+c[x][i].second;
				if(!inq[u]){
					inq[u]=true;
					Q.push(u);
				}
			}
		}
	}
}
double calc(double a,double b,double len){//两端点燃时间a,b,长度len
	if(a>b) swap(a,b);
	//a时刻,一端点燃,b时刻,另一端点燃
	if(b-a>=len) return a+len;//b点燃之前就烧完了
	len-=b-a;
	return b+len/2.0;//b点燃之后一起烧
}
void answer(void){
	double ans=0;
	for(int x=1;x<=N;x++){
		for(int i=0;i<c[x].size();i++){
			ans=max(ans,calc(f[x],f[c[x][i].first],c[x][i].second));
		}
	}
	printf("%.1lf\n",ans);
}
void init(void){
	scanf("%d",&M);
	N=M+1;
	int u,v,len;
	for(int i=1;i<=M;i++){
		scanf("%d%d%d",&u,&v,&len);
		addedge(u,v,len);
		addedge(v,u,len);
	}
	for(int i=1;i<=N;i++){
		if(c[i].size()==1){//叶子
			addedge(S,i,0);
		}
	}
}
int main(){
	freopen("firelead.in","r",stdin);
	freopen("firelead.out","w",stdout);
	init();
	SPFA();
	answer();
	return 0;
}