#include "bits/stdc++.h"
using namespace std;
using LL = long long;
static constexpr int N = 1e6+5;
vector<vector<array<int, 3>>> adj;
vector<array<int, 2>> par;
bitset<N> vis, cyc;
int cycle_node = -1;
int back_edge = -1;
void dfs(int v, int pi) {
vis[v] = true;
for (auto [u, w, i] : adj[v]) {
if (i == pi) continue; // deal with cycles of length 2
if (!vis[u]) {
par[u] = {v, w};
dfs(u, i);
} else if (vis[u] && cycle_node == -1) {
cycle_node = v;
par[u] = {v, w};
back_edge = i;
}
}
}
void find_diam(int v, int p, LL dist, array<LL, 2>& max_dist) {
max_dist = max(max_dist, array<LL, 2>{dist, v});
for (auto [u, w, i] : adj[v]) {
if (u == p || i == back_edge) continue;
find_diam(u, v, dist + w, max_dist);
}
}
LL height(int v, int p) {
LL ans = 0;
for (auto [u, w, i] : adj[v]) {
if (u == p || i == back_edge) continue;
if (cyc[u]) continue;
ans = max(ans, w + height(u, v));
}
return ans;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n; cin >> n;
adj.resize(n+1);
par.resize(n+1);
for (int v = 1, u, w; v <= n; ++v) {
cin >> u >> w;
adj[v].push_back({u, w, v});
adj[u].push_back({v, w, v});
}
LL ans = 0;
for (int v = 1; v <= n; ++v) {
if (!vis[v]) {
// first dfs
dfs(v, -1);
// diameter
array<LL, 2> max_dist{0, v};
find_diam(v, -1, 0, max_dist);
int u = max_dist[1];
max_dist = {0, u};
find_diam(u, -1, 0, max_dist);
LL diameter = max_dist[0];
// path traversing the cycle
LL a = cycle_node;
LL cycle_length = 0;
while (par[a][0] != cycle_node) {
cyc[a] = true;
cycle_length += par[a][1];
a = par[a][0];
}
cyc[a] = true;
cycle_length += par[a][1];
a = cycle_node;
LL max1 = -1e9, max2 = -1e9;
LL prv1 = height(a, -1);
LL prv2 = prv1;
while (par[a][0] != cycle_node) {
auto [b, w] = par[a];
prv1 += w;
prv2 -= w;
LL h = height(b, -1);
max1 = max(max1, prv1 + h);
max2 = max(max2, prv2 + h);
prv1 = max(prv1, h);
prv2 = max(prv2, h);
a = b;
}
LL cycle_path = max(max1, cycle_length + max2);
// increase the answer by the maximum path in the current cc
ans += max(diameter, cycle_path);
cycle_node = -1; // reset
back_edge = -1;
}
}
cout << ans << "\n";
}
