#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int ll
const int N = 300005;
int c[N], sz[N];
vector<int> fii[N];
struct Ura {
priority_queue<int> points;
int a, b;
} vura[N];
void join(Ura &a, Ura &b) {
a.a += b.a;
a.b += b.b;
while (!b.points.empty()) {
a.points.push(b.points.top());
b.points.pop();
}
}
void baga(Ura &a, int c) {
while (a.a > 1) {
a.a --;
a.b += a.points.top();
a.points.pop();
}
int x = a.points.top(); a.points.pop();
int y = a.points.top(); a.points.pop();
a.points.push(y + c);
a.points.push(x + c);
a.b -= c;
}
void dfs(int nod) {
sz[nod] = 1;
int fmax = 0;
for (auto i : fii[nod]) {
dfs(i);
sz[nod] += sz[i];
if (sz[fmax] < sz[i]) {
fmax = i;
}
}
if (fmax == 0) {
vura[nod].points.push(c[nod]);
vura[nod].points.push(c[nod]);
vura[nod].a = 1;
vura[nod].b = -c[nod];
return;
}
swap(vura[fmax], vura[nod]);
for (auto i : fii[nod]) {
if (i != fmax) {
join(vura[nod], vura[i]);
}
}
baga(vura[nod], c[nod]);
}
signed main() {
int n, m;
cin >> n >> m;
for (int i = 2; i <= n + m; i ++) {
int p;
cin >> p >> c[i];
fii[p].push_back(i);
}
c[1] = 1;
dfs(1);
auto a = vura[1];
while (a.a > 0) {
a.a --;
a.b += a.points.top();
a.points.pop();
}
cout << a.b << '\n';
}
