#include<bits/stdc++.h>
using namespace std;
#define int long long
#define in array<int, 2>
#define pb push_back
#define pob pop_back
#define fast() ios_base::sync_with_stdio(false); cin.tie(NULL)
const int MX = 2e5+5;
const int INF = 1e17;
vector<int> adj[MX];
int w[MX];
multiset<int> dp[MX];
int off[MX];//if you see value S, real value is S+off[u].
in T[MX];//final function is TRUE T[u][1]*X + T[u][0].
void dfs(int u)
{
if(adj[u].empty())
{
dp[u].insert(w[u]);
dp[u].insert(w[u]);
T[u] = {-w[u], 1};
off[u] = 0;
return;
}
for(int v: adj[u])
{
dfs(v);
if((dp[u].size() < dp[v].size()))
{
swap(dp[u], dp[v]);
swap(off[u], off[v]);
swap(T[u], T[v]);
}
T[u][0]+=T[v][0];
T[u][1]+=T[v][1];
for(int X: dp[v])
dp[u].insert(X+off[v]-off[u]);
dp[v].clear();
}
if(u == 1)
return;
while(T[u][1] > 1)
{
auto it = prev(dp[u].end());
T[u][1]--;
T[u][0]+=((*it) + off[u]);
dp[u].erase(it);
}
/*cout << "For vertex u " << u << " we have " << endl;
for(auto s: dp[u])
cout << (s+off[u]) << " ";
cout << endl;
cout << "! = " << T[u][1] << " " << T[u][0] << endl;*/
auto it = prev(dp[u].end());
int D = *it;
dp[u].erase(it);
T[u][1]--;
T[u][0]+=(D + off[u]);
dp[u].insert(D+w[u]-off[u]);
T[u][1]++;
T[u][0]-=(D+w[u]);
return;
}
signed main()
{
fast();
int n, m; cin >> n >> m; n+=m;
for(int i = 2; i <= n; i++)
{
int s; cin >> s >> w[i];
adj[s].pb(i);
}
dfs(1);
int ans = T[1][0];
while(T[1][1]--)
{
auto it = prev(dp[1].end());
ans+=(*it);
dp[1].erase(it);
}
cout << ans << "\n";
return 0;
}
