#include <bits/stdc++.h>
using namespace std;
const int N = 55;
const int INF = 0x3f3f3f3f;
template <typename T>
inline void read(T &AKNOI) {
  T x = 0, flag = 1;
  char ch = getchar();
  while (!isdigit(ch)) {
    if (ch == '-') flag = -1;
    ch = getchar();
  }
  while (isdigit(ch)) {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  AKNOI = flag * x;
}
template <typename T>
inline void cmin(T &x, T y) {
  if (x > y) x = y;
}
template <typename T>
inline void cmax(T &x, T y) {
  if (x < y) x = y;
}
int n, m, st;
vector<int> e[N];
int len[N][N], cnt[N];
int dp[N][N][N][N];
void DFS(int u, int fa) {
  for (auto v : e[u]) {
    if (v == fa) continue;
    DFS(v, u);
    cnt[u] += cnt[v];
  }
}
int DP(int u, int v, int c1, int c2) {
  if (!c1 && !c2) return 0;
  if (!c1) return INF;
  if (~dp[u][v][c1][c2]) return dp[u][v][c1][c2];
  if (e[v].size() == 1) {
    return dp[u][v][c1][c2] = len[u][v] + DP(v, u, c2, 0);
  }
  int tmp[N];
  memset(tmp, 0, sizeof(tmp));
  tmp[0] = INF;
  for (auto s : e[v]) {
    if (s == u) continue;
    for (int i = c1; i >= 0; --i) {
      for (int j = 0; j <= i; ++j) {
        cmax(tmp[i], min(tmp[i - j], DP(v, s, j, c1 - j + c2)));
      }
    }
  }
  return dp[u][v][c1][c2] = len[u][v] + tmp[c1];
}
void init() {
  read(n);
  for (int i = 1, u, v, w; i < n; ++i) {
    read(u);
    read(v);
    read(w);
    e[u].push_back(v);
    e[v].push_back(u);
    len[u][v] = len[v][u] = w;
  }
  read(st);
  read(m);
  for (int i = 1; i <= m; ++i) {
    int x;
    read(x);
    ++cnt[x];
  }
}
void solve() {
  DFS(st, 0);
  memset(dp, -1, sizeof(dp));
  int ans = INF;
  for (auto v : e[st]) {
    cmin(ans, DP(st, v, cnt[v], m - cnt[v]));
  }
  printf("%d\n", ans);
}
int main() {
  init();
  solve();
  return 0;
}
