#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define fr first
#define sc second
#define clr(a, x) memset(a, x, sizeof(a))
#define dbg(x) cout<<"("<<#x<<"): "<<x<<endl;
#define printvector(arr) for (auto it = arr.begin(); it != arr.end(); ++it) cout<<*it<<" "; cout<<endl;
#define all(v) v.begin(), v.end()
#define lcm(a, b) (a * b)/__gcd(a, b)
#define int long long int
#define printvecpairs(vec) for(auto it: vec) cout<<it.fr<<' '<<it.sc<<endl;
#define endl '\n'
#define float long double
const int MOD = 1e9 + 7;
const int INF = 2e15;
const int MAXN = 2e5 + 5;
vector<int> adj[MAXN];
int val[MAXN], timer = 0, sz[MAXN], arr[MAXN];
int dfs(int s){
int curr = ++timer;
arr[curr] = val[s];
sz[curr] = 1;
for(auto u: adj[s]){
sz[curr] += dfs(u);
}
return sz[curr];
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
#ifdef LOCAL
freopen("input.txt", "r", stdin);
#endif
int n, m;
cin>>n>>m;
int root = -1;
for(int i= 1;i<=n;i++){
int t1, t2;
cin>>t1>>t2;
val[i] = t2;
if(t1 == 0){
root = i;
continue;
} else {
adj[t1].pb(i);
}
}
dfs(root);
int dp[n+3][2];
for(int i =1;i<=n+1;i++){
dp[i][0] = 0;
}
for(int i =1;i<=m;i++){
dp[n+1][i%2] = -INF;
for(int j= n;j>=1;j--){
dp[j][i%2] = max(dp[j+1][i%2], dp[j+sz[j]][(i-1)%2] + arr[j]);
}
}
cout<<dp[1][m%2]<<endl;
return 0;
}
