#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MAX = 1e6;
int n;
int deg[MAX + 26];
int dp[MAX + 25];
bool vis[MAX + 25];
pair <int, int> nxt[MAX + 25];
vector <pair <int, int>> adj[MAX + 26];
struct Mono {
int sze = 0;
stack <pair <int, int>> s1, s2;
int get_min () {
if (s1.empty() || s2.empty()) {
return s1.empty() ? s2.top().second : s1.top().second;
} else {
return max(s1.top().second, s2.top().second);
}
}
void insert (int x) {
int mn = s1.empty() ? x : max(x, s1.top().second);
s1.push({x, mn});
sze++;
}
void remove () {
if (s2.empty()) while (!s1.empty()) {
int x = s1.top().first; s1.pop();
int mn = (s2.empty() ? x : max(x, s2.top().second));
s2.push({x, mn});
}
s2.pop();
sze--;
}
};
int dp2[MAX + 25][2];
int diameter (int x, int t, int par) {
if (adj[x].empty()) return 0;
if (adj[x].size() == 1 && par != -1) return 0;
if (dp2[x][t] != -1) return dp2[x][t];
int mx1 = 0, mx2 = 0;
int mx3 = 0;
for (auto j : adj[x]) {
if (j.first == par) continue;
int sum = j.second + diameter(j.first, 0, x);
if (sum > mx1) {
mx2 = mx1;
mx1 = sum;
} else if (sum > mx2) {
mx2 = sum;
}
mx3 = max(mx3, diameter(j.first, 1, x));
}
if (t) return dp2[x][t] = max(mx3, mx1 + mx2);
return dp2[x][t] = mx1;
}
vector <int> l;
vector <int> l2;
signed main () {
ios::sync_with_stdio(0);
cin.tie(0);
memset(dp2, -1, sizeof(dp2));
cin >> n;
for (int i = 1; i <= n; i++) {
int x, y;
cin >> x >> y;
nxt[i] = {x, y};
deg[x]++;
}
queue <int> cur;
for (int i = 1; i <= n; i++) {
if (!deg[i]) {
cur.push(i);
}
}
while (!cur.empty()) {
int k = cur.front();
cur.pop();
auto j = nxt[k];
dp[j.first] = max(dp[j.first], j.second + dp[k]);
adj[j.first].push_back({k, j.second});
adj[k].push_back(j);
deg[j.first]--;
if (deg[j.first] == 0) {
cur.push(j.first);
}
}
int sum = 0;
for (int i = 1; i <= n; i++) {
if (!vis[i] && deg[i]) {
int cur = i;
Mono ddd;
l.clear(); l2.clear();
int mx2 = diameter(i, 1, -1);
l.push_back(dp[i]);
l2.push_back(0);
vis[i] = 1;
int cnt = 1;
while (nxt[cur].first != i) {
cnt++;
mx2 = max(mx2, diameter(nxt[cur].first, 1, -1));
l.push_back(dp[nxt[cur].first]);
l2.push_back(nxt[cur].second);
cur = nxt[cur].first;
vis[cur] = 1;
}
l.push_back(dp[nxt[cur].first]);
l2.push_back(nxt[cur].second);
cur = nxt[cur].first;
while (nxt[cur].first != i) {
l.push_back(dp[nxt[cur].first]);
l2.push_back(nxt[cur].second);
cur = nxt[cur].first;
}
int xx = l2.size();
int pref[xx] = {};
for (int j = 1; j < xx; j++) {
pref[j] = l2[j] + pref[j - 1];
}
ddd.insert(l[0]);
for (int j = 1; j < xx; j++) {
mx2 = max(mx2, l[j] + pref[j] + ddd.get_min());
ddd.insert(l[j] - pref[j]);
if (ddd.sze >= cnt) {
ddd.remove();
}
}
sum += mx2;
}
}
cout << sum << '\n';
}
