#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long
// 217
// 44
using namespace std;
const ll INF = 1e18;
struct Edge {
int nod, cst;
int id;
};
vector < vector <Edge> > g;
vector < pair <int, int> > cyc;
vector <int> nodes, vis, deg;
void get_cyc(int nod) {
queue <int> Q;
Q.push(nod), vis[nod] = 1;
while(Q.size()) {
nod = Q.front(), nodes.push_back(nod);
Q.pop();
for(auto it : g[nod]) {
if(vis[it.nod] == 0) {
vis[it.nod] = 1;
Q.push(it.nod);
}
}
}
for(auto it : nodes) {
vis[it] = 0;
if(deg[it] == 1) {
Q.push(it);
vis[it] = 1;
}
}
while(Q.size()) {
nod = Q.front();
Q.pop();
for(auto it : g[nod]) {
deg[it.nod]--;
if(deg[it.nod] == 1) {
Q.push(it.nod);
vis[it.nod] = 1;
}
}
}
for(auto it : nodes) {
if(vis[it] == 0) {
nod = it;
break;
}
}
int root = nod, flag = 1, id = 0;
vis[nod] = 1;
while(flag) {
for(auto it : g[nod]) {
if(vis[it.nod] == 0) {
vis[it.nod] = 1;
cyc.push_back({nod, it.cst});
id = it.id, nod = it.nod;
break;
}
else if(it.nod == root && it.id != id) {
cyc.push_back({nod, it.cst});
flag = 0;
}
}
}
}
vector <ll> dp1, dp2;
void dfs(int nod, ll &ans) {
vector <int> Q;
int sz = 0;
Q.push_back(nod);
vis[nod] = 1;
while(sz < Q.size()) {
nod = Q[sz++];
for(auto it : g[nod]) {
if(vis[it.nod] == 0) {
vis[it.nod] = 2;
Q.push_back(it.nod);
}
}
}
reverse(Q.begin(), Q.end());
for(auto nod : Q) {
dp1[nod] = dp2[nod] = 0;
for(auto it : g[nod]) {
if(vis[it.nod] == 1) {
continue;
}
ll cur = dp1[it.nod] + it.cst;
if(dp1[nod] <= cur) {
dp2[nod] = dp1[nod];
dp1[nod] = cur;
}
else if(dp2[nod] < cur) {
dp2[nod] = cur;
}
}
ans = max(ans, dp1[nod] + dp2[nod]);
}
}
inline ll solve(int nod) {
cyc.clear(), nodes.clear();
get_cyc(nod);
for(auto it : nodes) {
vis[it] = 0;
}
ll sum = 0;
for(auto it : cyc) {
vis[it.first] = 1;
sum += it.second;
}
ll cur = 0, mx1 = -INF, mx2 = -INF, ans = 0;
for(auto it : cyc) {
dfs(it.first, ans);
if(it.first != cyc[0].first) {
ans = max(ans, max(mx1 + dp1[it.first] + cur, mx2 + dp1[it.first] - cur));
}
mx1 = max(mx1, dp1[it.first] - cur);
mx2 = max(mx2, dp1[it.first] + cur + sum);
cur += it.second;
}
return ans;
}
int main() {
//ifstream cin("A.in");
//ofstream cout("A.out");
int i, n;
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
cin >> n;
g.resize(n + 1), deg.resize(n + 1);
for(i = 1; i <= n; i++) {
int nod, cst;
cin >> nod >> cst;
g[i].push_back({nod, cst, i});
g[nod].push_back({i, cst, i});
deg[i]++, deg[nod]++;
}
vis.resize(n + 1);
dp1.resize(n + 1, -INF), dp2.resize(n + 1, -INF);
ll ans = 0;
for(i = 1; i <= n; i++) {
if(vis[i] == 0) {
ans += solve(i);
}
}
cout << ans;
//cin.close();
//cout.close();
return 0;
}
