#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>using namespace std;#define N 220000#define inf 0x3ffffffffffffffLLtypedef long long ll;int v[N],e[N],ne[N],nn,w[N];void add(int x,int y,int z){    ne[++nn]=e[x],e[x]=nn,v[nn]=y,w[nn]=z;}int n;int dfn[N];int tot;int fa[N],ww[N*2],f2[N];int bb,b1[N*2];ll ss[N*2];void dfs(int x){    dfn[x]=++tot;    for(int i=e[x];i;i=ne[i]){        if(fa[x]==v[i])continue;        if(!dfn[v[i]]){            fa[v[i]]=x;            f2[v[i]]=w[i];            dfs(v[i]);        }else{            if(dfn[v[i]]>dfn[x]){                for(int j=v[i];j!=x;j=fa[j]){                    b1[++bb]=j;                    ww[bb]=f2[j];                }                b1[++bb]=x;                ww[bb]=w[i];            }        }    }}int been[N];ll dp1[N],dp2[N];ll ans2;int q1[N*2],he1,bo1;int q2[N*2],he2,bo2;ll v1[N*2],v2[N*2];void dfs2(int x,int fa){    for(int i=e[x];i;i=ne[i]){        if(fa==v[i]||been[v[i]])continue;        dfs2(v[i],x);        ans2=max(ans2,dp1[x]+dp1[v[i]]+w[i]);        dp1[x]=max(dp1[x],dp1[v[i]]+w[i]);    }}ll ma;void gg(int x,int y){    if(q1[x]!=q2[y]){      ma=max(ma,v1[x]+v2[y]);        }}int main(){    scanf("%d",&n);    for(int i=1;i<=n;i++){        int a,b,c;        scanf("%d%d%d",&a,&b,&c);        add(a,b,c);        add(b,a,c);    }    dfs(1);    for(int i=1;i<=bb;i++)been[b1[i]]=1;    for(int i=1;i<=bb;i++){        dfs2(b1[i],0);    }  for(int i=1;i<=bb;i++)ww[i+bb]=ww[i],b1[i+bb]=b1[i];  for(int i=1;i<=bb*2;i++)ss[i]=ss[i-1]+(ll)ww[i];   ll ans=inf;   q1[he1=bo1=1]=1;   q2[he2=bo2=1]=1;   q1[++he1]=2;   q2[++he2]=2;   for(int i=3;i<=bb*2;i++){       if(i-q1[bo1]>=bb)bo1++;       if(i-q2[bo2]>=bb)bo2++;       ma=0;       while(he1>bo1+1&&v1[he1]>v1[he1-1]){           swap(v1[he1],v1[he1-1]);           swap(q1[he1],q1[he1-1]);           he1--;            }       while(he2>bo2+1&&v2[he2]>v2[he2-1]){          swap(v2[he2],v2[he2-1]);          swap(q2[he2],q2[he2-1]);              he2--;        }       q1[++he1]=i;       q2[++he2]=i;       v1[he1]=dp1[b1[i]]+ss[i-1];       v2[he2]=dp1[b1[i]]-ss[i-1];       if(i>bb){          gg(bo1,bo2);          gg(bo1,bo2+1);          gg(bo1,he2);          gg(bo1+1,bo2);          gg(bo1+1,bo2+1);          gg(bo1+1,he2);          gg(he1,bo2);          gg(he1,bo2+1);          ans=min(ans,ma);       }            }    ans=max(ans,ans2);  if(ans%2LL==0LL){       printf("%lld.0",ans/2LL);        }else{       printf("%lld.5",ans/2LL);        }  }