#include <traffic.h>
#include <vector>
#define MAXN 1000000
using namespace std;
int p[MAXN]; // parent
int pop[MAXN];\
vector<int> adj[MAXN];
int ans[MAXN];
void dfs(int x, int y) {//y is back edge
p[x] = y;
ans[x] = pop[x];
for (int e : adj[x]) {
if (e == y) continue;
dfs(e, x);
ans[x] += ans[e];
}
}
int LocateCentre(int N, int P[], int S[], int D[]) {
for (int i = 0; i < N - 1; i++) {
pop[i] = P[i];
adj[S[i]].push_back(D[i]);
adj[D[i]].push_back(S[i]);
}
pop[N-1] = P[N - 1];
dfs(0, -1);
int mn = 2000000005;
int ansi = 0;
for (int i = 0; i < N; i++) {
int mx = 0;
for (int val : adj[i]) {
mx = max(mx, p[i] == val ? ans[0] - ans[i] : ans[val]);
}
if (mx < mn) {
mn = mx;
ansi = i;
}
}
return ansi;
}
