#pragma GCC target("avx2,avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using i128 = __int128_t;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define all(x) (x).begin(), (x).end()
constexpr char ln = '\n';
istream& operator>>(istream& is, __int128_t& x) {
    x = 0;
    string s;
    is >> s;
    int n = int(s.size()), it = 0;
    if (s[0] == '-') it++;
    for (; it < n; it++) x = (x * 10 + s[it] - '0');
    if (s[0] == '-') x = -x;
    return is;
}
ostream& operator<<(ostream& os, __int128_t x) {
    if (x == 0) return os << 0;
    if (x < 0) os << '-', x = -x;
    deque<int> deq;
    while (x) deq.emplace_front(x % 10), x /= 10;
    for (int e : deq) os << e;
    return os;
}
template<class T1, class T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& p) {
    return os << "(" << p.first << ", " << p.second << ")";
}
template<class T> 
ostream& operator<<(ostream& os, const vector<T>& v) {
    os << "{";
    for (int i = 0; i < int(v.size()); i++) {
        if (i) os << ", ";
        os << v[i];
    }
    return os << "}";
}
template<class Container> inline int SZ(Container& v) { return int(v.size()); }
template<class T> inline void UNIQUE(vector<T>& v) { v.erase(unique(v.begin(), v.end()), v.end()); }
template<class T1, class T2> inline bool chmax(T1& a, T2 b) { if (a < b) {a = b; return true ;} return false ;}
template<class T1, class T2> inline bool chmin(T1& a, T2 b) { if (a > b) {a = b; return true ;} return false ;}
inline int topbit(ull x) { return x == 0 ? -1 : 63 - __builtin_clzll(x); }
inline int botbit(ull x) { return x == 0 ? 64 : __builtin_ctzll(x); }
inline int popcount(ull x) { return __builtin_popcountll(x); }
inline int kthbit(ull x, int k) { return (x>>k) & 1; }
inline constexpr long long TEN(int x) { return x == 0 ? 1 : TEN(x-1) * 10; }
inline void print() { cout << "\n"; }
template<class T>
inline void print(const vector<T>& v) {
    for (int i = 0; i < int(v.size()); i++) {
        if (i) cout << " ";
        cout << v[i];
    }
    print();
}
template<class T, class... Args>
inline void print(const T& x, const Args& ... args) {
    cout << x << " ";
    print(args...);
}
#ifdef MINATO_LOCAL
inline void debug_out() { cerr << endl; }
template <class T, class... Args>
inline void debug_out(const T& x, const Args& ... args) {
    cerr << " " << x;
    debug_out(args...);
}
#define debug(...) cerr << __LINE__ << " : [" << #__VA_ARGS__ << "] =", debug_out(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " : " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif
struct fast_ios { fast_ios() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

template<typename T>
struct edge {
    int src,to;
    T cost;
    int id;

    edge(){}
    edge(int to, T cost) : src(-1), to(to), cost(cost), id(-1) {}
    edge(int src, int to, T cost) : src(src), to(to), cost(cost), id(-1) {}
    edge(int src, int to, T cost, int id) : src(src), to(to), cost(cost), id(id) {}
    bool operator<(const edge &e) const {return cost < e.cost;}
};

struct Node {
    ll cost;
    int id;
    Node() {}
    Node(ll cost, int id) : cost(cost), id(id) {}
    bool operator<(const Node &rhs) const {return cost < rhs.cost;}
};

constexpr ll INF = 1e18;

int main() {
    int N,Q,C; cin >> N >> Q >> C;
    vector<vector<edge<ll>>> G(N);
    rep(i,N-1) {
        int u,v,w; cin >> u >> v >> w;
        u--; v--;
        G[u].emplace_back(v,w);
        G[v].emplace_back(u,w);
    }
    vector<int> x(Q);
    rep(i,Q) cin >> x[i], x[i]--;

    vector<vector<ll>> dist(N, vector<ll>(N,-1));
    queue<int> que;
    rep(i,N) {
        dist[i][i] = 0;
        que.emplace(i);
        while (!que.empty()) {
            int v = que.front(); que.pop();
            for (auto& e : G[v]) {
                if (~dist[i][e.to]) continue;
                dist[i][e.to] = dist[i][v]+e.cost;
                que.emplace(e.to);
            }
        }
    }

    vector<ll> dp(N,INF);
    dp[x[0]] = 0;
    vector<Node> arr(N);
    vector<ll> nex(N);
    vector<int> seen(N);
    rep(k,Q-1) {
        rep(i,N) {
            if (i==x[k]) arr[i] = Node(dp[i]+dist[i][x[k+1]],i);
            else arr[i] = Node(dp[i]+dist[i][x[k+1]]+C,i);
        }
        sort(all(arr));
        fill(all(seen),0);
        rep(i,N) nex[i] = dp[i]+dist[x[k]][x[k+1]];
        chmin(nex[x[k+1]],arr[0].cost);
        seen[x[k+1]] = 1;

        rep(i,N) {
            ll val = arr[i].cost;
            int s = arr[i].id;
            auto dfs=[&](auto self, int v, int pv)->bool {
                if (seen[v]) return true;
                for (auto& e : G[v]) {
                    if (e.to==pv) continue;
                    if (dist[x[k+1]][e.to] > dist[x[k+1]][v]) continue;
                    if (self(self,e.to,v)) {
                        chmin(nex[v],val);
                        seen[v] = 1;
                        return true;
                    }
                }
                return false;
            };
            dfs(dfs,s,-1);
        }
        swap(dp,nex);
    }

    cout << *min_element(all(dp)) << ln;
}