/*
it could have been better :)
it will next time ;)
*/
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF 1e18
#define f first
#define s second
#define pii pair<int, int>
#define vi vector<int>
const int MOD = 1'000'000'000 + 7;
void setIO(string name = "")
{
ios_base::sync_with_stdio(0);
cin.tie(0), cout.tie(0);
#ifdef LOCAL
freopen("inp.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#else
if (!name.empty())
{
freopen((name + ".INP").c_str(), "r", stdin);
freopen((name + ".OUT").c_str(), "w", stdout);
}
#endif
}
// START OF DEBUG
#define db(val) "["#val" = "<<(val)<<"] "
#define print_op(...) ostream& operator<<(ostream& out, const __VA_ARGS__& u)
template<class U, class V> print_op(pair<U, V>) {
return out << "(" << u.first << ", " << u.second << ")";
}
template<class Con, class = decltype(begin(declval<Con>()))>
typename enable_if<!is_same<Con, string>::value, ostream&>::type
operator<<(ostream& out, const Con& con) {
out << "{";
for (auto beg = con.begin(), it = beg; it != con.end(); ++it)
out << (it == beg ? "" : ", ") << *it;
return out << "}";
}
template<size_t i, class T> ostream& print_tuple_utils(ostream& out, const T& tup) {
if constexpr(i == tuple_size<T>::value) return out << ")";
else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup);
}
template<class ...U> print_op(tuple<U...>) {
return print_tuple_utils<0, tuple<U...>>(out, u);
}
// END OF DEBUG
const int MAXN = 1e5;
int n;
vector<tuple<int, int, int>> g[MAXN + 5];
int dfs_diameter(int u, int p_edge_id, pii skip, int &mx) {
vi a;
for(auto [v, w, id] : g[u]) {
if(id == p_edge_id || v == skip.f || v == skip.s) continue;
a.push_back(dfs_diameter(v, id, skip, mx) + w);
}
sort(a.rbegin(), a.rend());
pii cur = {0, 0};
if(a.size() > 0) cur.f = cur.s = a[0];
if(a.size() > 1) cur.s += a[1];
mx = max(mx, cur.s);
return cur.f;
}
bool vis[MAXN + 5];
pii par[MAXN + 5];
bool found_cycle = true;
int st = -1, en = -1;
int cycle_w = -1;
void dfs_cycle(int u, int p_edge_id = -1) {
if(p_edge_id == -1) {
found_cycle = false;
st = -1, en = -1;
cycle_w = -1;
}
vis[u] = true;
for(auto [v, w, id] : g[u]) {
if(id == p_edge_id) continue;
if(vis[v]) {
if(!found_cycle) {
st = u, en = v;
found_cycle = true;
cycle_w = w;
}
}
else {
par[v] = {u, w};
dfs_cycle(v, id);
}
}
}
vector<pii> find_cycle() {
if(st == -1) return {};
vector<pii> cycle;
int cur = st;
while(cur != en && cur != 0) {
cycle.push_back({cur, par[cur].second});
cur = par[cur].first;
}
if(cur == 0) return {};
cycle.push_back({en, cycle_w});
reverse(cycle.begin(), cycle.end());
return cycle;
}
int f[MAXN + 5];
void solve()
{
cin >> n;
for(int i = 1; i <= n; i++) {
int j; cin >> j;
int w; cin >> w;
g[i].push_back({j, w, i});
g[j].push_back({i, w, i});
}
int res = 0;
for(int i = 1; i <= n; i++) {
if(vis[i]) continue;
dfs_cycle(i);
vector<pii> cycle = find_cycle();
int m = cycle.size();
for(int i = 0; i < m; i++) {
cycle.push_back(cycle[i]);
dfs_diameter(cycle[i].f, -1, {cycle[(i - 1 + m) % m].f, cycle[(i + 1) % m].f}, f[cycle[i].f]);
}
m = cycle.size();
vi ps(m);
for(int i = 1; i < m; i++) ps[i] = ps[i - 1] + cycle[i].s;
multiset<int> ms;
ms.insert(f[cycle[0].f]);
int cur = 0;
for(int i = 1; i < m; i++) {
cur = max(cur, f[cycle[i].f] + ps[i] - *ms.rbegin());
ms.insert(f[cycle[i].f] - ps[cycle[i].f] + cycle[i].s);
if(i >= m) {
ms.erase(ms.find((f[cycle[i - m].f] - ps[cycle[i - m].f] + cycle[i - m].s)));
}
}
res += cur;
// cout << cycle << '\n';
}
cout << res << '\n';
}
signed main()
{
setIO();
int t = 1;
// cin >> t;
while (t--)
solve();
}
