#include <bits/stdc++.h>
#define pii pair<int, int>
#define x first
#define y second
using namespace std;
const int N = 2e5 + 10;
int dp[N][2], va[N], n;
vector<pii> g[N];
void pre( int u, int p, int vv ) {
va[u] = vv;
for( pii v : g[u] ) if( v.x != p ) {
pre( v.x, u, v.y );
}
}
void dfs( int u, int p ) {
//printf("%d %d\n",u,p);
vector<int> vec;
int cnt = g[u].size();
if( u != 1 ) cnt--;
if( !cnt ) return void( dp[u][1] = -1e9 );
if( cnt == 1 ) {
for( pii x : g[u] ) if( x.x != p ) {
int v = x.x;
dfs( v, u );
dp[u][0] = max( dp[v][0], va[v] + dp[v][1] );
dp[u][1] = dp[v][0] + va[v];
}
return ;
}
for( pii x : g[u] ) if( x.x != p ) {
int v = x.x;
dfs( v, u );
//printf("NODE U P V : %d %d %d %d %d\n",u,p,v,dp[v][0],dp[v][1]);
int mx = max( dp[v][0], dp[v][1] + va[v] );
dp[u][0] += mx, dp[u][1] += mx;
//printf("%d\n",mx);
vec.emplace_back( va[v] + dp[v][0] - mx );
}
sort( vec.begin(), vec.end(), greater<int>() );
/*for( int i : vec ) printf("%d ",i);
printf("\n");*/
if( vec[0] + vec[1] > 0 ) dp[u][0] += vec[0] + vec[1];
dp[u][1] += vec[0];
//printf("%d %d %d\n",u,dp[u][0],dp[u][1]);
return ;
}
int main()
{
scanf("%d",&n);
for( int i = 1, a, b, c ; i < n ; i++ ) {
scanf("%d %d %d",&a,&b,&c);
g[a].emplace_back( b, c ), g[b].emplace_back( a, c );
}
pre( 1, 0, 0 ), dfs( 1, 0 );
printf("%d",dp[1][0]);
return 0;
}
