#define DEBUG 0
#include <bits/stdc++.h>
using namespace std;
#if DEBUG
// basic debugging macros
int __i__,__j__;
#define printLine(l) for(__i__=0;__i__<l;__i__++){cout<<"-";}cout<<endl
#define printLine2(l,c) for(__i__=0;__i__<l;__i__++){cout<<c;}cout<<endl
#define printVar(n) cout<<#n<<": "<<n<<endl
#define printArr(a,l) cout<<#a<<": ";for(__i__=0;__i__<l;__i__++){cout<<a[__i__]<<" ";}cout<<endl
#define print2dArr(a,r,c) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<a[__i__][__j__]<<" ";}cout<<endl;}
#define print2dArr2(a,r,c,l) cout<<#a<<":\n";for(__i__=0;__i__<r;__i__++){for(__j__=0;__j__<c;__j__++){cout<<setw(l)<<setfill(' ')<<a[__i__][__j__]<<" ";}cout<<endl;}
// advanced debugging class
// debug 1,2,'A',"test";
class _Debug {
public:
template<typename T>
_Debug& operator,(T val) {
cout << val << endl;
return *this;
}
};
#define debug _Debug(),
#else
#define printLine(l)
#define printLine2(l,c)
#define printVar(n)
#define printArr(a,l)
#define print2dArr(a,r,c)
#define print2dArr2(a,r,c,l)
#define debug
#endif
// define
#define MAX_VAL 999999999
#define MAX_VAL_2 999999999999999999LL
#define EPS 1e-6
#define mp make_pair
#define pb push_back
// typedef
typedef unsigned int UI;
typedef long long int LLI;
typedef unsigned long long int ULLI;
typedef unsigned short int US;
typedef pair<int,int> pii;
typedef pair<LLI,LLI> plli;
typedef vector<int> vi;
typedef vector<LLI> vlli;
typedef vector<pii> vpii;
typedef vector<plli> vplli;
// ---------- END OF TEMPLATE ----------
vpii adjList[200000];
int dp[200000][4];
int doDFS(int u,int p) {
int i;
int m = -MAX_VAL,m2 = -MAX_VAL,m3 = 0;
vi child,w;
dp[u][1] = dp[u][2] = dp[u][3] = 0;
for (i = 0; i < adjList[u].size(); i++) {
int v = adjList[u][i].first;
if (v != p) {
child.pb(v),w.pb(adjList[u][i].second);
doDFS(v,u);
dp[u][2] += max(dp[v][3]+adjList[u][i].second,dp[v][2]);
m = max(m,dp[v][2]+adjList[u][i].second-max(dp[v][3]+adjList[u][i].second,dp[v][2]));
m2 = max(m2,dp[v][0]+adjList[u][i].second-max(dp[v][3]+adjList[u][i].second,dp[v][2]));
m3 = max(m3,max(dp[v][0],dp[v][1]+adjList[u][i].second)-max(dp[v][3]+adjList[u][i].second,dp[v][2]));
}
}
dp[u][3] = dp[u][2]+m,dp[u][1] = dp[u][2]+m2,dp[u][0] = dp[u][2]+m3;
m = m2 = -MAX_VAL;
int mi = -1;
for (i = 0; i < child.size(); i++) {
int v = child[i];
int d = dp[child[i]][0]+w[i]-max(dp[v][3]+w[i],dp[v][2]);
if (d >= m) m2 = m,m = d,mi = i;
else if (d >= m2) m2 = d;
}
for (i = 0; i < child.size(); i++) {
int v = child[i];
int d = dp[child[i]][2]+w[i]-max(dp[v][3]+w[i],dp[v][2]);
if (i == mi) dp[u][0] = max(dp[u][0],dp[u][2]+d+m2);
else dp[u][0] = max(dp[u][0],dp[u][2]+d+m);
}
return 0;
}
int main() {
int i;
int n;
int a,b,c;
scanf("%d",&n);
for (i = 1; i < n; i++) {
scanf("%d %d %d",&a,&b,&c);
a--,b--;
adjList[a].pb(mp(b,c));
adjList[b].pb(mp(a,c));
}
doDFS(0,-1);
printf("%d\n",dp[0][0]);
return 0;
}
