#include <bits/stdc++.h>
using namespace std;
int n;
int dp[200005][2][2];
bool f[200005];
vector <pair <int, int> > v[200005];
void dfs(int nod = 1, int TT = 0){
f[nod] = 1;
int Sum = 0, Max = -2000000000, Max1 = -2000000000, Max2 = -2000000000;
for(auto it : v[nod]){
if(f[it.first]) continue ;
dfs(it.first, it.second);
Sum = Sum + max(dp[it.first][0][0], dp[it.first][0][1]);
Max = max(Max, max(dp[it.first][1][0], dp[it.first][1][1]) - max(dp[it.first][0][0], dp[it.first][0][1]));
Max1 = max(Max1, dp[it.first][0][0] + it.second - max(dp[it.first][0][0], dp[it.first][0][1]));
Max2 = max(Max2, dp[it.first][1][0] + it.second - max(dp[it.first][0][0], dp[it.first][0][1]));
}
dp[nod][0][0] = max(0, Sum);
dp[nod][1][0] = max(0, Sum + Max);
if(nod != 1){
dp[nod][0][1] = max(0, Sum + Max1 + TT);
dp[nod][1][1] = max(0, Sum + Max2 + TT);
}
Max1 = -2000000000, Max2 = -2000000000;
for(auto it : v[nod]){
if(f[it.first]) continue ;
dp[nod][1][0] = max(dp[nod][1][0], Sum + Max1 + max(dp[it.first][0][0], dp[it.first][1][0]) + it.second - max(dp[it.first][0][0], dp[it.first][0][1]));
dp[nod][1][0] = max(dp[nod][1][0], Sum + Max2 + dp[it.first][0][0] + it.second - max(dp[it.first][0][0], dp[it.first][0][1]));
Max1 = max(Max1, dp[it.first][0][0] + it.second - max(dp[it.first][0][0], dp[it.first][0][1]));
Max2 = max(Max2, dp[it.first][1][0] + it.second - max(dp[it.first][0][0], dp[it.first][0][1]));
}
f[nod] = 0;
}
int main()
{
scanf("%d", &n);
int x, y, l;
for(int i = 1; i < n ; ++i){
scanf("%d%d%d", &x, &y, &l);
v[x].push_back({y, l});
v[y].push_back({x, l});
}
dfs();
printf("%d", max(max(dp[1][0][0], dp[1][1][0]), max(dp[1][0][1], dp[1][1][1])));
return 0;
}
/*
10
4 10 2
1 2 21
1 3 13
6 7 1
7 9 5
2 4 3
2 5 8
1 6 55
6 8 34
*/
