[Ioi2005]River

#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstring>
#include<algorithm>
#define maxn 105
#define inf 1061109567
using namespace std;
char ch;
int n,k,a,b,c,tot,w[maxn],now[maxn],son[maxn],pre[maxn],val[maxn];
int dist[maxn],f[maxn][maxn][maxn],tmp[maxn][maxn][maxn];
bool ok,bo[maxn][maxn];
void read(int &x){
    for (ok=0,ch=getchar();!isdigit(ch);ch=getchar()) if (ch==‘-‘) ok=1;
    for (x=0;isdigit(ch);x=x*10+ch-‘0‘,ch=getchar());
    if (ok) x=-x;
}
void put(int a,int b,int c){pre[++tot]=now[a],now[a]=tot,son[tot]=b,val[tot]=c;}
int turn(int x){if (x==inf) return 0;return x;}
void dfs(int u,int last){
    if (bo[u][last]) return;
    bo[u][last]=1;
    for (int p=now[u],v=son[p];p;p=pre[p],v=son[p]){
        dist[v]=dist[u]+val[p];
        dfs(v,last),dfs(v,v);
        for (int i=0;i<=k;i++){
            f[u][last][i]=inf;
            for (int j=0;j<=i;j++){
                if (i>j) f[u][last][i]=min(f[u][last][i],tmp[u][last][i-j-1]+f[v][v][j]);
                f[u][last][i]=min(f[u][last][i],tmp[u][last][i-j]+f[v][last][j]+w[v]*(dist[v]-dist[last]));
            }
        }
        memcpy(tmp[u][last],f[u][last],sizeof(tmp[u][last]));
    }
}
int main(){
    read(n),read(k);
    for (int i=1;i<=n;i++) read(w[i]),read(b),read(c),put(b,i,c);
    dfs(0,0);
    printf("%d\n",f[0][0][k]);
    return 0;
}