#include <bits/stdc++.h>
using namespace std;
const int N = 55;
int n, cnt, s, m, du[N], G[N], w[N];
int f[N][N][N][N];
int d[N][N];
struct edge {
  int t, nx, w;
} E[N << 1];
inline void add(int x, int y, int z) {
  E[++cnt].t = y;
  E[cnt].nx = G[x];
  G[x] = cnt;
  du[x]++;
  E[++cnt].t = x;
  E[cnt].nx = G[y];
  G[y] = cnt;
  du[y]++;
  d[x][y] = d[y][x] = z;
}
int dfs(int x, int f) {
  int ret = w[x];
  for (int i = G[x]; i; i = E[i].nx)
    if (E[i].t != f) ret += dfs(E[i].t, x);
  return ret;
}
int dp(int u, int v, int frnt, int bck) {
  if (frnt == 0 && bck == 0) return 0;
  int &ret = f[u][v][frnt][bck];
  if (ret) return ret;
  if (du[v] == 1) {
    if (bck == 0) return 0;
    return ret = dp(v, u, bck, 0) + d[u][v];
  }
  int g[N];
  for (int i = 1; i <= frnt; i++) g[i] = -(1 << 30);
  g[0] = 1 << 30;
  for (int i = G[v]; i; i = E[i].nx) {
    int vv = E[i].t;
    if (vv == u) continue;
    for (int j = frnt; j; j--)
      for (int k = 1; k <= j; k++)
        g[j] =
            max(g[j], min(g[j - k], dp(v, vv, k, frnt + bck - k) + d[v][vv]));
  }
  return ret = g[frnt];
}
int main() {
  scanf("%d", &n);
  for (int i = 1, x, y, z; i < n; i++)
    scanf("%d%d%d", &x, &y, &z), add(x, y, z);
  scanf("%d%d", &s, &m);
  for (int i = 1, x; i <= m; i++) scanf("%d", &x), w[x]++;
  int ans = 1 << 30;
  for (int i = G[s]; i; i = E[i].nx) {
    int num = dfs(E[i].t, s);
    ans = min(ans, dp(s, E[i].t, num, m - num) + d[E[i].t][s]);
  }
  printf("%d\n", ans);
  return 0;
}
