/*input
7
3 8
7 2
4 2
1 4
1 9
3 4
2 3
*/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll ans(vector<pair<ll, ll>> &A)
{
ll n = A.size() / 2;
ll mx = 0;
ll S[2 * n];
S[0] = 0;
for (int i = 1; i < 2 * n; i++)
S[i] = S[i - 1] + A[i - 1].second;
deque<int>Q;
for (int j = 0; j < 2 * n; j++)
{
while (!Q.empty() && Q.front() <= j - n)
Q.pop_front();
if (!Q.empty())
{
int i = Q[0];
mx = max(mx, S[j] + A[j].first + (A[i].first - S[i]));
}
while (!Q.empty() && A[Q.back()].first - S[Q.back()] < A[j].first - S[j])
Q.pop_back();
Q.push_back(j);
}
return mx;
}
int main()
{
ios_base::sync_with_stdio(false);
ll N;
cin >> N;
ll pa[N + 1];
ll L[N + 1];
ll K[N + 1];
fill_n(K, N + 1, 0ll);
ll H[N + 1];
fill_n(H, N + 1, 0ll);
ll MX[N + 1];
fill_n(MX, N + 1, 0ll);
for (ll i = 1; i <= N; i++)
{
cin >> pa[i] >> L[i];
K[pa[i]]++;
}
for (ll i = 1; i <= N; i++)
{
if (pa[i] != 0)
{
ll j = i;
while (K[j] == 0)
{
ll k = pa[j];
MX[k] = max({MX[j], MX[k], H[k] + H[j] + L[j]});
H[k] = max(H[k], H[j] + L[j]);
K[k]--;
pa[j] = 0;
j = k;
}
}
}
ll ret = 0;
for (ll i = 1; i <= N; i++)
{
if (pa[i] != 0)
{
ll gal = 0;
vector<pair<ll, ll>>A;
ll j = i;
while (pa[j] != 0)
{
gal = max(gal, MX[j]);
A.push_back({H[j], L[j]});
ll k = pa[j];
pa[j] = 0;
j = k;
}
ll s = A.size();
for (ll j = 0; j < s; j++)
A.push_back(A[j]);
ret += max(gal, ans(A));
}
}
cout << ret << "\n";
}
