#include <stdio.h>
#include <stdlib.h>
#define N 200000
int max(int a, int b) { return a > b ? a : b; }
int *ej[N], *ec[N], eo[N];
void append(int i, int j, int c) {
int o = eo[i]++;
if (o >= 2 && (o & o - 1) == 0) {
ej[i] = (int *) realloc(ej[i], o * 2 * sizeof *ej[i]);
ec[i] = (int *) realloc(ec[i], o * 2 * sizeof *ec[i]);
}
ej[i][o] = j, ec[i][o] = c;
}
int dp[N][2];
void dfs(int p, int c_, int i) {
int o, x0, x1, x2;
x0 = 0, x1 = -1, x2 = -1;
for (o = eo[i]; o--; ) {
int j = ej[i][o], c = ec[i][o];
if (j != p) {
dfs(i, c, j);
x2 = max(x2 == -1 ? -1 : x2 + dp[j][0], x1 == -1 ? -1 : x1 + dp[j][1]);
x1 = max(x1 == -1 ? -1 : x1 + dp[j][0], x0 + dp[j][1]);
x0 += dp[j][0];
}
}
dp[i][0] = x1 == -1 ? 0 : x1 + c_, dp[i][1] = max(x0, x2) + c_;
}
int main() {
int n, h, i, j, c;
scanf("%d", &n);
for (i = 0; i < n; i++) {
ej[i] = (int *) malloc(2 * sizeof *ej[i]);
ec[i] = (int *) malloc(2 * sizeof *ec[i]);
}
for (h = 0; h < n - 1; h++) {
scanf("%d%d%d", &i, &j, &c), i--, j--;
append(i, j, c), append(j, i, c);
}
dfs(-1, 0, 0);
printf("%d\n", dp[0][1]);
return 0;
}
