#pragma GCC optimize("O3")
#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#define fi first
#define se second
#define pc __builtin_popcount
constexpr int MAXN = 1 << 20;
vector<tuple<int, int, int>> grafo[MAXN];
pair<int, int> succ[MAXN];
int vis[MAXN];
bool cycle[MAXN];
pair<ll, ll> dist[MAXN];
bool dfs1(int v, int x) {
if (vis[v] == 2) {
return false;
} else if (vis[v] == 1) {
cycle[v] = true;
return true;
}
vis[v] = 1;
for (auto [u, w, z] : grafo[v]) {
if (x == z) continue;
if (dfs1(u, z)) {
succ[v] = {u, w};
} else {
succ[u] = {v, w};
}
}
vis[v] = 2;
return succ[v].fi != 0;
}
void dfs2(int v) {
for (auto [u, w, _] : grafo[v]) {
if (cycle[u] || u == succ[v].fi) continue;
dfs2(u);
dist[v].fi = max({dist[v].fi, dist[u].fi, dist[v].se + dist[u].se + w});
dist[v].se = max(dist[v].se, dist[u].se + w);
}
}
int main() {
ios::sync_with_stdio(false);
int N;
cin >> N;
for (int i = 1; i <= N; i++) {
int b, c;
cin >> b >> c;
grafo[i].emplace_back(b, c, i);
grafo[b].emplace_back(i, c, i);
}
for (int i = 1; i <= N; i++) {
if (vis[i] == 0) dfs1(i, 0);
if (!cycle[i]) continue;
for (int j = succ[i].fi; j != i; j = succ[j].fi) {
cycle[j] = true;
}
}
for (int i = 1; i <= N; i++) {
if (cycle[i]) dfs2(i);
}
vector<pair<ll, int>> Q;
Q.reserve(N);
ll sum_res = 0;
for (int i = 1; i <= N; i++) {
if (!cycle[i] || vis[i] == 8) continue;
Q.clear();
ll res = 0;
ll path = 0;
for (int j = i, gen = 0; vis[j] != 4; j = succ[j].fi, ++gen) {
vis[j] = 4;
Q.emplace_back(path + dist[j].se, gen);
path += succ[j].se;
res = max(res, dist[j].fi);
}
make_heap(Q.begin(), Q.end());
ll tot = path;
for (int j = i, gen = 0; vis[j] != 8; j = succ[j].fi, ++gen) {
vis[j] = 8;
while (Q[0].se <= gen) {
pop_heap(Q.begin(), Q.end());
Q.pop_back();
}
res = max(res, Q[0].fi - path + tot + dist[j].se);
Q.emplace_back(path + dist[j].se, MAXN);
push_heap(Q.begin(), Q.end());
path += succ[j].se;
}
sum_res += res;
}
cout << sum_res << endl;
return 0;
}
