#include "bits/stdc++.h"
#include "race.h"
using namespace std;
using ll = long long;
using vi = vector<ll>;
using pi = pair<long long, long long>;
#define pb emplace_back
#define fr first
#define sc second
const int mxN = 1005;
const ll inf = 1e15;
vector<pi> adj[mxN];
pi dep[mxN];
void dfs(int x, int p, int d, int l) {
dep[x].fr = d;
dep[x].sc = l;
for(auto [i, w] : adj[x]) {
if(i != p) {
dfs(i, x, d + 1, l + w);
}
}
}
int best_path(int N, int K, int H[][2], int L[])
{
for(int i = 0; i < N - 1; ++i) {
adj[H[i][0]].pb(H[i][1], L[i]);
adj[H[i][1]].pb(H[i][0], L[i]);
}
ll ans = inf;
for(int i = 0; i < N; ++i) {
pi id = {0, 0};
fill(dep, dep + mxN, id);
dfs(i, -1, 0, 0);
for(int j = 0; j < N; ++j) {
if(dep[j].sc == K)
ans = min(ans, dep[j].fr);
}
}
return (ans == inf ? -1 : ans);
}
