#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define endl "\n"
#define ll long long
#define IOS ios_base::sync_with_stdio(false); cin.tie(nullptr);
const int N = 3e5 + 5;
const ll INF = 1e18;
vector<pair<int, int>> adj[N];
int parent[N];
int sz[N];
multiset<ll> st[N];
int dsu_find(int p) {
if (parent[p] == p) {
return p;
}
parent[p] = dsu_find(parent[p]);
return parent[p];
}
void dsu_merge(int a, int b) {
if (st[a].size() > st[b].size()) {
swap(a, b);
}
parent[a] = b;
for (auto x : st[a]) {
st[b].insert(x);
}
return;
}
void dfs(int u, int p) {
sz[u] = 0;
int c = 1;
for (auto [v, wt] : adj[u]) {
if (v != p) {
c = 0;
dfs(v, u);
sz[u] += sz[v];
int a = dsu_find(u), b = dsu_find(v);
while (st[b].size() > sz[v] + 1) {
auto it = st[b].end();
it--;
st[b].erase(it);
}
auto it = st[b].end();
it--;
ll y = *it;
it--;
ll x = *it;
st[b].erase(st[b].find(x));
st[b].erase(st[b].find(y));
st[b].insert(x + wt);
st[b].insert(y + wt);
dsu_merge(a, b);
}
}
if (c) {
sz[u] = 1;
st[u].insert(0);
st[u].insert(0);
}
}
int main() {
IOS;
int n, m;
cin >> n >> m;
n += m;
ll ans = 0;
for (int i = 0; i < n; i++) {
parent[i] = i;
if (i == 0) {
continue;
}
int p, wt;
cin >> p >> wt;
ans += wt;
p--;
adj[p].push_back({i, wt});
adj[i].push_back({p, wt});
}
dfs(0, 0);
int a = dsu_find(0);
vector<ll> points;
auto it = st[a].begin();
for (int i = 0; i < m; i++) {
points.push_back(*it);
it = st[a].erase(it);
}
ll last = 0; int ct = m;
for (int i = 0; i < m; i++) {
ans -= (points[i] - last) * ct;
last = points[i];
ct--;
}
cout << ans;
return 0;
}
