#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define sub(u) d(t[u], t[u] + s[u] - 1)
#define dis(u) d(t[u], t[u])
#define w (a[e][1])
#define v() (e == u ? a[e][0] : e)
const int LIM = 1e6;
template<class T> struct SegmentTree{
int n = LIM, i; T a[2*LIM] ;
SegmentTree& operator[](int j){ i=j+n; return *this; }
void operator=(T v){
for(a[i]=v; i/=2; ) a[i] = max(a[2*i], a[2*i+1]); }
T operator()(int l, int r){
T x = 0;
for(l+=n, r+=n+1; l<r; l/=2, r/=2){
if(l & 1) x = max(x, a[l++]);
if(r & 1) x = max(x, a[--r]);
}
return x;
}
};
vector<int> g[LIM];
array<int, 2> a[LIM];
int r, p[LIM], dfsTimer, t[LIM], s[LIM];
ll best;
bitset<LIM> vis;
SegmentTree<ll> d;
void dfs(int u){
s[u] = 1, t[u] = dfsTimer++;
for(int e : g[u]) if(e != r && !s[v()]){
p[v()] = u;
d[dfsTimer] = v() == r ? 0LL : dis(u) + (ll)w;
dfs(v());
s[u] += s[v()];
best = max(best, d(t[u], t[v()]-1) + sub(v()) - 2*dis(u));
}
}
void findCycle(int u, int par){
vis[u] = 1;
for(int e : g[u]) if(e != par){
if(vis[v()]) return void(r = e);
findCycle(v(), e);
if(r >= 0) return;
}
vis[u] = 0;
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
int n; cin >> n;
for(int i=0; i<n; ++i){
cin >> a[i][0] >> a[i][1]; --a[i][0];
g[a[i][0]].push_back(i);
g[i].push_back(i);
}
fill(p, p+n, -1);
ll ans = 0;
for(int z=0; z<n; ++z){
if(s[z]) continue;
r = -1, best = 0;
findCycle(z, -1);
bool cycle = r >= 0;
if(!cycle) r = z;
dfsTimer = 0;
dfs(r);
if(!cycle){
ans += best;
continue;
}
assert(cycle);
int u = a[r][0], last = -1;
ll res = 0, ex;
while(u != r){
ll mx = 0;
for(int e : g[u])
if(e != r && v() != p[u] && v() != last) mx = max(mx, sub(v()) - dis(u));
ex = max(d(0, t[u]-1), d(t[u]+s[u], dfsTimer-1));
res = max(res, dis(a[r][0]) - dis(u) + mx + ex);
last = u;
u = p[u];
}
res += a[r][1];
ans += max(best, res);
for(int i=0; i<dfsTimer; ++i) d[i] = 0;
}
cout << ans;
}
