#include<bits/stdc++.h>
using namespace std;
#define name "main"
typedef long long ll;
typedef pair<int,int> ii;
typedef pair<int,ll> iil;
#define fi first
#define se second
const int N = (int)1e6;
vector<ii> ke[N+2];
int cost[N+2],gi[N+2],vis[N+2],n,cha[N+2],arr[N+2],sz=0,times=0;
ll dep[N+2]={};
bool com[N+2];
void add_edge(int u , int v , int w){
ke[u].push_back({v,w});
ke[v].push_back({u,w});
}
void search(int u , int p){
vis[u] = ++times;
for (auto& x:ke[u]){
int v=x.fi,w=x.se;
if (v==p) continue;
if (!vis[v]) {
cha[v]=u;
gi[v]=w;
search(v,u);
}
else{
if (vis[v]<vis[u]) continue;
++sz;
cost[sz]=w;
arr[sz]=v;
for (; v!=u; v=cha[v]){
++sz;
arr[sz]=cha[v];
cost[sz]=gi[v];
}
}
}
return ;
}
// the component has at most 1 cycle inside ~
ll mx,ans=0;
int pos,root;
void dfs(int u , int p , ll s){
if (mx < s){
mx = s;
pos = u;
}
for (auto& x:ke[u]){
int v=x.fi,w=x.se;
if ((com[v]&&v!=root)||v==p) continue;
dfs(v,u,s+w);
}
return;
}
void giai(){
ll addmore = -1;
for (int i = 1; i <= sz; ++i) com[arr[i]] = true;
for (int i = 1; i <= sz; ++i){
mx=pos=root=-1;
dfs(arr[i],0,0);
dep[i]=mx;
root=arr[i];
dfs(pos,0,0);
addmore = max(addmore,mx);
}
deque<iil> q;
ll sum = 0;
for (int i = 1; i <= sz*2; ++i){
int x = (i <= sz ? dep[i] : dep[i - sz]);
sum += (i <= sz ? cost[i] : cost[i - sz]);
while (q.size() && q.front().fi < i - sz + 1) q.pop_front();
if (q.size()){
addmore = max(addmore,sum+x+q.front().se);
}
ll c = x - sum;
while (q.size() && q.back().se <= c) q.pop_back();
q.push_back({i,c});
}
ans+=addmore;
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin>>n;
for (int i=1; i<=n; ++i){
int en,l; cin>>en>>l;
add_edge(i,en,l);
}
for (int i=1; i<=n; ++i){
if (!vis[i]){
sz = times = 0;
search(i,i);
giai();
}
}
cout<<ans;
exit(0);
}
