#include <bits/stdc++.h>
#define fi first
#define se second
///Input format is not always nice, first nodes may not be in the keychain ring
using namespace std;
typedef long long ll;
typedef pair<int,int> ii;
typedef pair<ll, int> li;
int n;
vector<ii> G[1000005];
ll P[1000005];
int D[1000005];
int Pct;
int vis[1000005];
ll ANS;
ll ans;
int cyclehead;
void dfs(int u, int p){
vis[u] = 2;
int join =0;
int ct = 0;
for (auto v: G[u]){
if (vis[v.fi] & 2){
if (v.fi == p){
if (ct == 1){
cyclehead = p;
//printf("%d %d repeated\n",u,v.fi);
vis[u] |= 4;
join = v.se;
}
else {
ct++;
}
continue;
}
cyclehead = v.fi;
vis[u] |= 4;
join = v.se;
continue;
}
if (vis[v.fi]) continue;
dfs(v.fi,u);
if ((vis[v.fi]&4) && v.fi != cyclehead) {
vis[u] |= 4;
join = v.se;
continue;
}
}
if (vis[u] & 4){
//printf("at %d : %d\n",u,join);
P[Pct] = u;
D[Pct] = join;
Pct++;
}
vis[u] ^= 3;
}
ll dfs2(int u, int p){
ll d2 = 0;
ll d = 0;
for (auto v: G[u]){
if (v.fi == p || (vis[v.fi]&4)) continue;
ll nd = dfs2(v.fi,u)+v.se;
if (d <= nd){
d2 = d;
d = nd;
}
else d2 = max(d2,nd);
}
ans = max(ans,d2+d);
return d;
}
ll solve(int root){
ans = Pct = 0;
dfs(root,-1);
//printf("at %d\n",root);
reverse(P,P+Pct);
reverse(D,D+Pct);
for (int i = 0; i < Pct; i++){
P[i] = dfs2(P[i],-1);
//printf("%d: %d %d\n",x.fi,d[x.fi],x.se);
}
if (Pct == 2){
return max(ans,P[0]+P[1]+max(D[0],D[1]));
}
ll S = 0;
ll Sl = 0;
for (int i = 0; i < Pct; i++){
S += D[i];
}
ll MX = P[0];
ll MX2 = P[0];
for (int i = 1; i < Pct; i++){
ll x = P[i];
//printf("at %lld %lld\n",d[x],Sl[x]);
//printf("MX: %lld + %lld\n",MX,d[x] + Sl[x]);
//printf("MX2: %lld + %lld\n",MX2,S + d[x] - Sl[x]);
Sl += D[i-1];
ans = max(ans, x + Sl + MX);
ans = max(ans, S + x - Sl + MX2);
MX = max(MX, x - Sl);
MX2 = max(MX2, x + Sl);
}
//printf("%lld max\n",ans);
return ans;
}
int main(){
scanf("%d",&n);
for (int i = 1; i <= n; i++){
int j,L;
scanf("%d%d",&j,&L);
G[i].push_back({j,L});
G[j].push_back({i,L});
}
for (int i = 1; i <= n; i++){
if (vis[i] == 0){
ANS += solve(i);
}
}
printf("%lld",ANS);
}
