#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
const int LIM = 1e6;
set<pair<int, int>> length_two_cycle;
vector<pair<int, int>> adj[LIM + 1];
vector<int> cycle, cycle_weight, st, weight;
bool part_of_cycle[LIM + 1], vis[LIM + 1];
int vis_cycle[LIM + 1];
ll max_length = 0;
bool dfs_cycle(int cur, int par = -1, int last_weight = 0) {
vis_cycle[cur]++;
st.push_back(cur); weight.push_back(last_weight);
for(auto elem : adj[cur]) {
if(elem.first == par) {
if(length_two_cycle.count(make_pair(cur, par))) {
cycle.push_back(st.back()); cycle_weight.push_back(weight.back()); part_of_cycle[st.back()] = 1;
cycle.push_back(elem.first); cycle_weight.push_back(elem.second); part_of_cycle[elem.first] = 1;
return 1;
}
continue;
}
if(!vis_cycle[elem.first]) {
if(dfs_cycle(elem.first, cur, elem.second)) {
return 1;
}
}
else if(vis_cycle[elem.first] == 1) {
while(st.back() != elem.first) {
cycle.push_back(st.back()); cycle_weight.push_back(weight.back());
part_of_cycle[st.back()] = 1;
st.pop_back(); weight.pop_back();
}
part_of_cycle[elem.first] = 1;
cycle.push_back(elem.first); cycle_weight.push_back(elem.second);
return 1;
}
}
st.pop_back(); weight.pop_back();
vis_cycle[cur]++;
return 0;
}
ll dfs(int cur, int par = -1, int last_weight = 0) {
vis[cur] = 1;
ll first_max = 0, second_max = 0;
for(auto elem : adj[cur]) {
if(part_of_cycle[elem.first] || elem.first == par)continue;
ll length = dfs(elem.first, cur, elem.second);
if(length >= first_max) {
second_max = first_max;
first_max = length;
}
else if(length >= second_max) {
second_max = length;
}
}
max_length = max(max_length, first_max + second_max);
return (ll)last_weight + first_max;
}
void solve() {
int N; cin >> N;
map<pair<int, int>, int> to_add;
for(int i = 1; i <= N; ++i) {
int u, l; cin >> u >> l;
adj[i].push_back(make_pair(u, l));
if(to_add.count(make_pair(i, u))) {
to_add.erase(make_pair(i, u));
length_two_cycle.insert(make_pair(i, u));
length_two_cycle.insert(make_pair(u, i));
}
else {
to_add[make_pair(u, i)] = l;
}
}
for(auto elem : to_add) {
adj[elem.first.first].push_back(make_pair(elem.first.second, elem.second));
}
ll answer = 0;
for(int i = 1; i <= N; ++i) {
if(!vis[i]){
vector<int>().swap(cycle);
vector<int>().swap(st);
vector<int>().swap(cycle_weight);
vector<int>().swap(weight);
dfs_cycle(i);
max_length = 0;
ll total_length = 0, current_length = 0, regular_max = -1e18, reverse_max = -1e18;
// for(int j = 0; j < cycle.size(); ++j) {
// cout << cycle[j] << " " << cycle_weight[j] << "\n";
// }
for(int elem : cycle_weight) {
total_length += (ll)elem;
}
for(int j = 0; j < cycle.size(); ++j) {
ll depth = dfs(cycle[j]);
if(j > 0) {
max_length = max(max_length, regular_max + depth + current_length);
max_length = max(max_length, reverse_max + depth - current_length + total_length);
}
regular_max = max(regular_max, depth - current_length);
reverse_max = max(reverse_max, depth + current_length);
current_length += cycle_weight[j];
//cout << "| " << cycle[j] << " " << current_length << " " << regular_max << " " << reverse_max << "\n";
}
//cout << max_length << "\n";
answer += max_length;
}
}
cout << answer;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int tc = 1; //cin >> tc;
while(tc--) {
solve();
}
return 0;
}
