#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)
template<typename T>
void amin(T &a, T b) {
a = min(a,b);
}
template<typename T>
void amax(T &a, T b) {
a = max(a,b);
}
#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif
/*
figured out the solution from multiple sources
*/
const int MOD = 1e9 + 7;
const int N = 3e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
vector<pll> adj[N];
vector<ll> final_slope(N);
priority_queue<ll> pq[N];
void dfs1(ll u, ll pw){
if(adj[u].empty()){
pq[u].push(pw);
pq[u].push(pw);
final_slope[u] = 1;
return;
}
for(auto [v,w] : adj[u]){
dfs1(v,w);
while(!pq[v].empty()){
pq[u].push(pq[v].top());
pq[v].pop();
}
final_slope[u] += final_slope[v];
}
while(final_slope[u] >= 2){
final_slope[u]--;
pq[u].pop();
}
vector<ll> vals;
rep1(iter,2){
vals.pb(pq[u].top());
pq[u].pop();
}
trav(x,vals){
pq[u].push(x+pw);
}
}
void solve(int test_case)
{
ll n,m; cin >> n >> m;
ll sumw = 0;
for(int i = 2; i <= n+m; ++i){
ll p,w; cin >> p >> w;
adj[p].pb({i,w});
sumw += w;
}
dfs1(1,0);
while(final_slope[1] >= 1){
final_slope[1]--;
pq[1].pop();
}
ll ans = sumw;
while(!pq[1].empty()){
ans -= pq[1].top();
pq[1].pop();
}
cout << ans << endl;
}
int main()
{
fastio;
int t = 1;
// cin >> t;
rep1(i, t) {
solve(i);
}
return 0;
}
