#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
long long powmod(long long a, long long b) {
  long long res = 1;
  a %= mod;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
  }
  return res;
}
const int inf = 0x20202020, N = 55;
int n, u, v, w, dp[N][N][N][N], pd[N][N], g[N][N], s, m, cnt[N];
vector<int> e[N], nxt[N][N];
void dfs2(int u, int f) {
  for (auto v : e[u])
    if (v != f) {
      dfs2(v, u);
      cnt[u] += cnt[v];
    }
}
int gao(int u, int v, int sz1, int sz2) {
  if (sz1 + sz2 == 0) return 0;
  if (sz1 == 0) return inf;
  int &r = dp[u][v][sz1][sz2];
  if (r != inf) return r;
  if (((int)(nxt[u][v]).size()) == 1 && nxt[u][v][0] == -1) {
    nxt[u][v].clear();
    for (auto w : e[v]) {
      if (w != u) nxt[u][v].push_back(w);
    }
  }
  vector<int> &pnt = nxt[u][v];
  if (pnt.empty()) {
    return r = g[u][v] + gao(v, u, sz2, 0);
  }
  for (int i = 0; i < ((int)(pnt).size()); i++)
    for (int k = 0; k < sz1 + 1; k++) gao(v, pnt[i], k, sz1 + sz2 - k);
  for (int i = 0; i < ((int)(pnt).size()) + 1; i++)
    for (int j = 0; j < sz1 + 1; j++) pd[i][j] = 0;
  pd[0][0] = inf;
  for (int i = 0; i < ((int)(pnt).size()); i++)
    for (int j = 0; j < sz1 + 1; j++)
      for (int k = 0; k < sz1 + 1 - j; k++) {
        pd[i + 1][j + k] = max(pd[i + 1][j + k],
                               min(pd[i][j], gao(v, pnt[i], k, sz1 + sz2 - k)));
      }
  return r = pd[((int)(pnt).size())][sz1] + g[u][v];
}
int main() {
  memset(dp, 0x20, sizeof(dp));
  scanf("%d", &n);
  for (int i = 1; i < n + 1; i++)
    for (int j = 1; j < n + 1; j++) nxt[i][j].push_back(-1);
  for (int i = 1; i < n; i++) {
    scanf("%d%d%d", &u, &v, &w), e[u].push_back(v), e[v].push_back(u);
    g[u][v] = g[v][u] = w;
  }
  scanf("%d", &s);
  scanf("%d", &m);
  for (int i = 0; i < m; i++) {
    scanf("%d", &u);
    cnt[u]++;
  }
  dfs2(s, 0);
  int ret = inf;
  for (auto v : e[s]) ret = min(ret, gao(s, v, cnt[v], m - cnt[v]));
  printf("%d\n", ret);
}
