#include <bits/stdc++.h>
using namespace std;
#ifdef tabr
#include "library/debug.cpp"
#else
#define debug(...)
#endif
const int N = (int) 1e6 + 10;
vector<int> g[N];
int l[N];
int e[N];
int was[N];
int pv[N];
int cycle[N];
long long d1[N];
long long d2[N];
int c1;
int c2;
int sz;
int dead;
long long t;
void dfs1(int v, int pe) {
was[v] = 1;
for (auto id : g[v]) {
if (id == pe) {
continue;
}
int to = v ^ id ^ e[id];
if (was[to]) {
if (c1 != -1) {
continue;
}
dead = id;
c1 = v;
c2 = to;
cycle[v]++;
if (pv[to] != -1) {
cycle[pv[to]]--;
}
continue;
}
pv[to] = v;
dfs1(to, id);
cycle[v] += cycle[to];
}
sz += cycle[v];
}
void dfs2(int v, int p, int cnt, long long now) {
cnt += cycle[v];
d1[cnt] = max(d1[cnt], now);
for (auto id : g[v]) {
int to = v ^ id ^ e[id];
if (to == p || id == dead) {
continue;
}
dfs2(to, v, cnt, now + l[id]);
}
}
long long dfs3(int v, int p, long long now) {
vector<long long> c;
for (auto id : g[v]) {
int to = v ^ id ^ e[id];
if (to == p || id == dead) {
continue;
}
c.emplace_back(dfs3(to, v, now + l[id]));
}
t = max(t, now);
if (c.empty()) {
return now;
}
sort(c.rbegin(), c.rend());
if (c.size() > 1) {
t = max(t, c[0] + c[1] - 2 * now);
}
return c[0];
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n;
cin >> n;
for (int i = 0; i < n; i++) {
int j;
cin >> j >> l[i];
j--;
e[i] = j;
g[i].emplace_back(i);
g[j].emplace_back(i);
}
for (int i = 0; i < n; i++) {
if (e[e[i]] == i) {
l[e[i]] = l[i] = max(l[e[i]], l[i]);
}
}
long long ans = 0;
for (int i = 0; i < n; i++) {
if (was[i]) {
continue;
}
c1 = -1, c2 = -1;
sz = 0;
dead = -1;
pv[i] = -1;
dfs1(i, -1);
for (int j = 0; j <= sz; j++) {
d1[j] = d2[j] = 0;
}
dfs2(c1, c2, 0, 0);
swap(d1, d2);
dfs2(c2, c1, 0, 0);
swap(d1, d2);
for (int j = 0; j < sz; j++) {
d1[j + 1] = max(d1[j + 1], d1[j]);
d2[j + 1] = max(d2[j + 1], d2[j]);
}
t = 0;
dfs3(c1, c2, 0);
dfs3(c2, c1, 0);
for (int j = 1; j < sz; j++) {
t = max(t, d1[j] + d2[sz - j] + l[dead]);
}
ans += t;
}
cout << ans << '\n';
return 0;
}
