#include <bits/stdc++.h>
#include <bits/extc++.h>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef __gnu_pbds::priority_queue<ll> pq;
long long aggiusta(int N, int M, vector<int> P, vector<int> L){
ll n = N; ll m = M;
vector<ll> l(n+m);
for(int i = 0; i<n+m; i++) l[i] = L[i];
l[0]=0;
vector<vector<int>> adj(N+M);
for(int i= 1; i<N+M; i++){
adj[P[i]].push_back(i);
adj[i].push_back(P[i]);
}
adj[0].push_back(-1);
auto dfs = [&](int v, int p, auto&& dfs) -> pq{
pq q;
if(v>=N){
q.push(l[v]);
q.push(l[v]);
return q;
}
for(int u: adj[v]){
if(u==p) continue;
pq q2 = dfs(u, v, dfs);
q.join(q2);
}
for(int i= 0; i<adj[v].size()-2; i++){
q.pop();
}
ll x1 = q.top(); q.pop();
ll x0 = q.top(); q.pop();
q.push(x1+l[v]);
q.push(x0+l[v]);
return q;
};
pq q;
q = dfs(0, -1, dfs);
vector<ll> slp;
while(!q.empty()){
slp.push_back(q.top());
q.pop();
}
//reverse(slp.begin(), slp.end());
ll dp0 = 0;
for(int i = 1; i<n+m; i++) dp0+=l[i];
ll slope = 1-slp.size();
ll lst = 0;
for(int i = slope; i<0; i++){
dp0 += i*(slp[-i]-lst);
lst = slp[-i];
}
return dp0;
}
int main(){
int n, m; cin >> n >> m;
vector<int> p(n+m);
vector<int> f(n+m);
for(int i= 0; i<n+m; i++){
cin >> p[i] >> f[i];
p[i]--;
}
cout << aggiusta(n, m, p, f) << '\n';
}
