#include "bits/stdc++.h"
using namespace std;
#define pii pair<int, int>
#define fi first
#define se second
#define pb push_back
const int nax = 1e6;
int n;
int p[nax+5];
bool vis[nax+5];
long long c[nax+5];
long long val[nax+5];
long long psum[nax+5];
vector<pii> adj[nax+5];
vector<int> cyc[nax+5];
vector<pii> edg;
void gp(int u, int par, int ls=0) {
p[u] = par;
for(pii t : adj[u]) {
int v = t.fi;
int e = t.se;
if(e == ls) continue;
if(p[v] == 0) {
gp(v, par, e);
} else {
cyc[par].push_back(e);
}
}
}
bool fc(int u, int go, int ls) {
if(u == go) return true;
for(pii t : adj[u]) {
int v = t.fi;
int e = t.se;
if(e == ls) continue;
bool ok = fc(v, go, e);
if(ok) {
vis[u] = true;
vis[v] = true;
cyc[p[go]].push_back(e);
return true;
}
}
return false;
}
long long trav(int u) {
if(val[u]) return val[u];
vis[u] = true;
long long res = 0;
for(pii t : adj[u]) {
int v = t.fi;
int e = t.se;
if(!vis[v]) {
res = max(res, c[e] + trav(v));
}
}
return val[u] = res;
}
long long sum (int l, int r, int i) {
if(r < l) return psum[r] + psum[cyc[i].size()-1] - psum[l-1];
if(l) return psum[r] - psum[l-1];
return psum[r];
}
int main () {
scanf("%d", &n);
edg.pb({0,0});
for(int i=1; i<=n; i++) {
long long l, j;
scanf("%lld %lld", &j, &l);
c[i] = l;
adj[j].pb({i,i});
adj[i].pb({j,i});
edg.pb({i,j});
}
long long ans = 0;
for(int i=1; i<=n; i++) {
if(p[i] == 0) {
gp(i,i);
cyc[i].pop_back();
fc(edg[cyc[i][0]].fi, edg[cyc[i][0]].se, cyc[i][0]);
long long opt = 0;
long long total = 0;
for(int q = 0; q < cyc[i].size(); q++) {
int k = cyc[i][q];
total += c[k];
psum[q] = c[k];
if(q) psum[q] += psum[q-1];
}
for(int q=0; q<cyc[i].size(); q++) {
for(int r=q; r < cyc[i].size(); r++) {
int u = edg[cyc[i][q]].fi;
int v = edg[cyc[i][r]].se;
if(u == v) continue;
opt = max(opt, trav(u) + trav(v) + max(sum(q,r, i), total - sum(q,r, i)));
}
}
ans += opt;
}
}
printf("%lld", ans);
}
