#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz(a) (int)a.size()
using ll = long long;
using ar2 = array<int,2>;
using ar3 = array<int,3>;
using vi = vector<int>;
const int mxN = (int)1e6+2;
vi w;
ll n, far, SS;
bitset<mxN> cyc;
int adj[3][mxN*2];
int adjH[mxN]; int8_t vis[mxN];
int allowed_S; bool curCnt = 0;
vi xd;
pair<ll,int> dfs2(int s) {
struct F { int s, x, bn; ll b, w; };
vector<F> st;
st.push_back({s, adjH[s], s, 0, 0});
vis[s]++;
while (!st.empty()) {
auto &f = st.back();
if (f.x) {
int e = f.x;
f.x = adj[1][e];
int u = adj[0][e];
ll w = adj[2][e];
if (vis[u] != curCnt) continue;
vis[u]++;
st.push_back({u, adjH[u], u, 0, w});
} else {
F t = st.back(); st.pop_back();
if (!st.empty()) {
ll cand = t.b + t.w;
if (cand > st.back().b) {
st.back().b = cand;
st.back().bn = t.bn;
}
} else return {t.b, t.bn};
}
}
return {0,0};
}
ll dfs(int s, int p) {
struct F { int s, x, par; ll b, w; };
vector<F> st;
st.push_back({s, adjH[s], p, 0, 0});
while (!st.empty()) {
auto &f = st.back();
if (f.x) {
int e = f.x;
f.x = adj[1][e];
int u = adj[0][e];
ll w = adj[2][e];
if (u == f.par || cyc[u]) continue;
st.push_back({u, adjH[u], f.s, 0, w});
} else {
auto t = st.back(); st.pop_back();
if (!st.empty()) {
ll cand = t.b + t.w;
if (cand > st.back().b)
st.back().b = cand;
} else return t.b;
}
}
return 0;
}
ll compute_diam(int s){
allowed_S = s; curCnt = 0;
int a = dfs2(s).second; curCnt=1;
return dfs2(a).first;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> n; ll ans = 0;
for(int i = 1; i <= n; i++){
int x, w; cin >> x >> w;
adj[0][i*2-1]=i, adj[1][i*2-1]=adjH[x],adj[2][i*2-1]=w; adjH[x]=i*2-1;
adj[0][i*2]=x, adj[1][i*2]=adjH[i],adj[2][i*2]=w; adjH[i]=i*2;
}
for(int i = 1; i <= n; i++){
if(vis[i]) continue;
int x = i; vi v; v.clear(); v.shrink_to_fit();
ll sum = 0, totP=0;
while(!vis[x]) vis[x]=1,v.pb(x),x=adj[0][x*2];
for(auto u : v) vis[u]=0; v.clear(); v.shrink_to_fit();
while(!cyc[x]) cyc[x]=1,v.pb(x),x=adj[0][x*2];
for(auto u : v) sum = max(sum, compute_diam(u));
int m = sz(v); multiset<ll> S; S.clear();
for(int i = 0; i < m; i++){
ll dis = dfs(v[i],0);
sum=max(sum,dis); S.insert(dis-totP);
totP+=(ll)adj[2][v[i]*2];
}
ll ss = 0;
for(int i = 0; i < m; i++){
ll dis = dfs(v[i],0);
S.erase(S.find(dis-ss));
if(sz(S)) sum=max(sum, dis+totP+ss+*prev(end(S)));
S.insert(dis-(totP+ss)); ss+=(ll)adj[2][v[i]*2];
}
ans+=sum;
}
cout << ans << "\n";
}
