#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<ll, ll>
#define fi first
#define sec second
#define ld long double
const int MAXN = 1e6;
const ll INF = 1e18;
const int MOD = 998244353;
const ld eps = 1e-6;
struct DSU{
ll N;
vector<ll> par;
DSU(ll _n){
N = _n;
par.resize(N + 5);
for(int i = 1; i <= N; i++) par[i] = i;
}
ll find(ll idx){
return (par[idx] == idx ? idx : par[idx] = find(par[idx]));
}
bool join(ll a, ll b){
a = find(a), b = find(b);
if(a == b) return false;
par[b] = a;
return true;
}
};
vector<pii> adj[MAXN + 5];
ll vis[MAXN + 5], dp[MAXN + 5][2];
void dfs(ll idx){
vis[idx] = 1;
ll sum = 0;
vector<ll> v;
for(auto [i, j] : adj[idx]){
if(!vis[i]){
dfs(i);
sum += max(dp[i][0], dp[i][1]);
v.push_back(dp[i][0] + j - max(dp[i][0], dp[i][1]));
}
}
dp[idx][0] = sum;
sort(v.begin(), v.end(), greater<ll>());
if(v.size() >= 1){
dp[idx][0] = max(dp[idx][0], sum + v[0]);
}
if(v.size() >= 2){
dp[idx][1] = max(dp[idx][1], sum + v[0] + v[1]);
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int tc = 1;
// cin >> tc;
for(;tc--;){
ll N; cin >> N;
vector<pair<ll, pii>> edges;
for(int i = 1; i <= N; i++){
ll idx, val; cin >> idx >> val;
edges.push_back({val, {i, idx}});
}
sort(edges.begin(), edges.end(), greater<pair<ll, pii>>());
DSU dsu(N);
for(auto [w, node] : edges){
if(dsu.join(node.fi, node.sec)){
adj[node.fi].push_back({node.sec, w});
adj[node.sec].push_back({node.fi, w});
}
}
ll ans = 0;
for(int i = 1; i <= N; i++){
if(!vis[i]){
dfs(i);
ans += max(dp[i][0], dp[i][1]);
}
}
cout << ans << "\n";
}
}
