#include <bits/stdc++.h>
#define pb push_back
#define all(v) ((v).begin(), (v).end())
#define sortv(v) sort(all(v))
#define sz(v) ((int)(v).size())
#define uniqv(v) (v).erase(unique(all(v)), (v).end())
#define umax(a, b) (a)=max((a), (b))
#define umin(a, b) (a)=min((a), (b))
#define FOR(i,a,b) for(int i = (a); i <= (b); i++)
#define rep(i,n) FOR(i,1,n)
#define rep0(i,n) FOR(i,0,(int)(n)-1)
#define FI first
#define SE second
#define INF 2000000000
#define INFLL 1000000000000000000LL
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, ll> pil;
const int MAX_N = 200000;
int N;
vector<pil> gp[MAX_N+1];
int p[MAX_N+1];
int c[MAX_N+1];
ll dp[MAX_N+1][4];
void dfs(int x){
for(auto i : gp[x]){
if(i.first==p[x]) continue;
p[i.first] = x;
c[i.first] = i.second;
dfs(i.first);
}
for(auto i : gp[x]) {
if(i.first==p[x]) continue;
dp[x][0] += max(dp[i.first][0], dp[i.first][2]);
}
ll mx = -INF;
dp[x][1] = dp[x][2] = dp[x][3] = -INF;
for(auto i : gp[x]){
if(i.first==p[x]) continue;
mx = max(mx, max(dp[i.first][1], dp[i.first][3]) - max(dp[i.first][0], dp[i.first][2]));
}
dp[x][1] = dp[x][0] + mx;
ll mx1 = -INF, mx2 = -INF;
for(auto i : gp[x]){
if(i.first==p[x]) continue;
dp[x][1] = max(dp[x][1], dp[x][0] + mx1 + dp[i.first][1] + i.second - max(dp[i.first][0], dp[i.first][2]));
dp[x][1] = max(dp[x][1], dp[x][0] + mx2 + dp[i.first][0] + i.second - max(dp[i.first][0], dp[i.first][2]));
dp[x][1] = max(dp[x][1], dp[x][0] + mx1 + dp[i.first][0] + i.second - max(dp[i.first][0], dp[i.first][2]));
mx1 = max(mx1, dp[i.first][0] + i.second - max(dp[i.first][0], dp[i.first][2]));
mx2 = max(mx2, dp[i.first][1] + i.second - max(dp[i.first][0], dp[i.first][2]));
}
for(auto i : gp[x]){
if(i.first==p[x]) continue;
dp[x][2] = max(dp[x][2], dp[x][0] + dp[i.first][0] + i.second - max(dp[i.first][0], dp[i.first][2]) + c[x]);
}
for(auto i : gp[x]){
if(i.first==p[x]) continue;
dp[x][3] = max(dp[x][3], c[x] + dp[x][0] + dp[i.first][1] + i.second - max(dp[i.first][0], dp[i.first][2]));
}
/*cout<<x<<endl;
for(int i=0; i<4; i++){
cout<<dp[x][i]<<' ';
}cout<<endl;*/
}
int main(){
scanf("%d", &N);
for(int i=0; i<N-1; i++){
int x, y; ll z;
scanf("%d%d%lld", &x, &y, &z);
gp[x].push_back({y, z}); gp[y].push_back({x, z});
}
dfs(1);
cout<<max(dp[1][0], dp[1][1]);
return 0;
}
