#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MAXN = 2e6 + 10;
const int INF = 1e18;
int pai[MAXN], marc[MAXN], deg[MAXN];
int dp[MAXN], dp2[MAXN];
pair<int, int> best[MAXN];
vector<pair<int, int>> adj[MAXN];
int n;
int tot = 0;
void lenhadora(){
queue<int> q;
for(int i=1; i<=n; i++) pai[i] = i;
for(int i=1; i<=n; i++){
if(deg[i] == 1){
q.push(i);
marc[i] = 1;
}
}
while(!q.empty()){
int v = q.front();
q.pop();
dp2[v] = max(dp2[v], best[v].first + best[v].second);
for(auto [u, w] : adj[v]){
deg[u] --;
if(marc[u]) continue;
pai[v] = u;
dp[u] = max(dp[u], dp[v] + w);
dp2[u] = max(dp2[u], dp2[v]);
if(dp[v] + w >= best[u].first){
best[u] = {dp[v] + w, best[u].first};
} else best[u].second = max(best[u].second, dp[v]);
if(deg[u] < 2){
q.push(u);
marc[u] = 1;
}
}
}
for(int i=1; i<=n; i++) marc[i] = 0;
}
void process(int v){
int cur = 0;
int max_a = -INF, max_b = -INF;
vector<pair<int, int>> cycle;
int sz = 0;
while(!marc[v]){
marc[v] = 1;
pair<int, int> nxt = {0, 0};
for(auto [u, w] : adj[v]){
if(!marc[u] && pai[u] == u){
if(nxt.first){
sz += w;
} else nxt = {u, w};
}
}
cycle.push_back({v, nxt.second});
sz += nxt.second;
v = nxt.first;
}
int d = 0;
for(auto [v, w] : cycle){
cur = max(cur, max_a + dp[v] + d);
cur = max(cur, max_b + dp[v] + sz - d);
cur = max(cur, dp2[v]);
max_a = max(max_a, dp[v] - d);
max_b = max(max_b, dp[v] + d);
d += w;
}
tot += cur;
}
int32_t main(){
cin.tie(0)->sync_with_stdio(0);
cin >> n;
for(int i=1; i<=n; i++){
int a, b; cin >> a >> b;
adj[i].push_back({a, b});
adj[a].push_back({i, b});
deg[i] ++; deg[a] ++;
}
lenhadora();
for(int i=1; i<=n; i++){
if(marc[i] || pai[i] != i) continue;
process(i);
}
cout << tot << "\n";
return 0;
}
