#include <bits/stdc++.h>
#define int long long
using namespace std;
typedef array<int, 2> pr;
const int MAX = 300001;
typedef array<int, 3> tp;
int N, M, V[MAX];
vector<int> adj[MAX];
priority_queue<int> dfs(int node) {
priority_queue<int> pq, tmp;
int X, Y;
if (node > N)
pq.push(0), pq.push(0);
for (int i : adj[node]) {
tmp = dfs(i);
if (tmp.size() > pq.size())
swap(tmp, pq);
while (!tmp.empty())
pq.push(tmp.top()), tmp.pop();
}
for (int i = 0; i + 1 < adj[node].size(); i++)
pq.pop();
X = pq.top(), pq.pop(), Y = pq.top(), pq.pop();
pq.push(X + V[node]), pq.push(Y + V[node]);
return pq;
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
int X, ans = 0;
priority_queue<int> pq;
cin >> N >> M;
for (int i = 2; i <= N + M; i++)
cin >> X >> V[i], adj[X].push_back(i), ans += V[i];
pq = dfs(1), pq.pop();
while (!pq.empty())
ans -= pq.top(), pq.pop();
cout << ans << '\n';
return 0;
}
