/*
it could have been better :)
it will next time ;)
*/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#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
}
const int MAXN = 1e6;
int n;
vector<tuple<int, int, int>> g[MAXN + 5];
ll dfs_diameter(int u, int p_edge_id, pii skip, ll &mx, ll &mx2) {
ll a0 = -1, a1 = -1;
for(auto [v, w, id] : g[u]) {
if(id == p_edge_id || v == skip.f || v == skip.s) continue;
ll cur = dfs_diameter(v, id, skip, mx, mx2) + w;
if(cur >= a0) {
a1 = a0;
a0 = cur;
}
else if(cur > a1) {
a1 = cur;
}
}
pair<ll, ll> cur = {0, 0};
if(a0 != -1) cur.f = cur.s = a0;
if(a1 != -1) cur.s += a1;
mx = max(mx, cur.f);
mx2 = max(mx2, cur.s);
return cur.f;
}
// bool vis[MAXN + 5];
bitset<MAXN + 5> vis;
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;
}
ll 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});
}
ll res = 0;
for(int i = 1; i <= n; i++) {
if(vis[i]) continue;
dfs_cycle(i);
vector<pii> cycle = find_cycle();
ll cur = 0;
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], cur);
}
vector<ll> ps(m * 2);
for(int i = 1; i < m * 2; i++) ps[i] = ps[i - 1] + cycle[i].s;
deque<int> dq;
dq.push_back(0);
for(int i = 1; i < m * 2; i++) {
while(!dq.empty() && dq.front() + m <= i) dq.pop_front();
cur = max(cur, f[cycle[i].f] + ps[i] + f[cycle[dq.front()].f] - ps[dq.front()]);
while(!dq.empty() && f[cycle[dq.back()].f] - ps[dq.back()] <= f[cycle[i].f] - ps[i]) dq.pop_back();
dq.push_back(i);
}
res += cur;
}
cout << res << '\n';
}
signed main()
{
setIO();
int t = 1;
// cin >> t;
while (t--)
solve();
}
