// >>> TEMPLATES
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
#define int ll
#define double ld
#define rep(i,n) for (int i = 0; i < (int)(n); i++)
#define rep1(i,n) for (int i = 1; i <= (int)(n); i++)
#define repR(i,n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep1R(i,n) for (int i = (int)(n); i >= 1; i--)
#define loop(i,a,B) for (int i = a; i B; i++)
#define loopR(i,a,B) for (int i = a; i B; i--)
#define all(x) begin(x), end(x)
#define allR(x) rbegin(x), rend(x)
#define rng(x,l,r) begin(x) + (l), begin(x) + (r)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fst first
#define snd second
template <class Int> auto constexpr inf = numeric_limits<Int>::max()/2-1;
auto constexpr INF32 = inf<int32_t>;
auto constexpr INF64 = inf<int64_t>;
auto constexpr INF   = inf<int>;
#ifdef LOCAL
#include "debug.hpp"
#else
#define dump(...) (void)(0)
#define say(x) (void)(0)
#define debug if (0)
#endif
template <class T, class Comp> struct pque : priority_queue<T, vector<T>, Comp> {
    vector<T> &data() { return this->c; }
    void clear() { this->c.clear(); }
};
template <class T> using pque_max = pque<T, less<T>>;
template <class T> using pque_min = pque<T, greater<T>>;
template <class T, class = typename T::iterator, enable_if_t<!is_same<T, string>::value, int> = 0>
ostream& operator<<(ostream& os, T const& a) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, size_t N, enable_if_t<!is_same<T, char>::value, int> = 0>
ostream& operator<<(ostream& os, const T (&a)[N]) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, class = decltype(begin(declval<T&>())), class = typename enable_if<!is_same<T, string>::value>::type>
istream& operator>>(istream& is, T &a) { for (auto& x : a) is >> x; return is; }
template <class T, class S> ostream& operator<<(ostream& os, pair<T,S> const& p) { return os << p.first << " " << p.second; }
template <class T, class S> istream& operator>>(istream& is, pair<T,S>& p) { return is >> p.first >> p.second; }
struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup;
template <class F> struct FixPoint : private F {
    constexpr FixPoint(F&& f) : F(forward<F>(f)) {}
    template <class... T> constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward<T>(x)...); }
};
struct MakeFixPoint { template <class F> constexpr auto operator|(F&& f) const { return FixPoint<F>(forward<F>(f)); } };
#define MFP MakeFixPoint()|
#define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__)
template <class T, size_t d> struct vec_impl {
    using type = vector<typename vec_impl<T,d-1>::type>;
    template <class... U> static type make_v(size_t n, U&&... x) { return type(n, vec_impl<T,d-1>::make_v(forward<U>(x)...)); }
};
template <class T> struct vec_impl<T,0> { using type = T; static type make_v(T const& x = {}) { return x; } };
template <class T, size_t d = 1> using vec = typename vec_impl<T,d>::type;
template <class T, size_t d = 1, class... Args> auto make_v(Args&&... args) { return vec_impl<T,d>::make_v(forward<Args>(args)...); }
template <class T> void quit(T const& x) { cout << x << endl; exit(0); }
template <class T, class U> constexpr bool chmin(T& x, U const& y) { if (x > y) { x = y; return true; } return false; }
template <class T, class U> constexpr bool chmax(T& x, U const& y) { if (x < y) { x = y; return true; } return false; }
template <class It> constexpr auto sumof(It b, It e) { return accumulate(b, e, typename iterator_traits<It>::value_type{}); }
template <class T> int sz(T const& x) { return x.size(); }
template <class C, class T> int lbd(C const& v, T const& x) { return lower_bound(begin(v), end(v), x)-begin(v); }
template <class C, class T> int ubd(C const& v, T const& x) { return upper_bound(begin(v), end(v), x)-begin(v); }
const int dx[] = { 1,0,-1,0,1,-1,-1,1 };
const int dy[] = { 0,1,0,-1,1,1,-1,-1 };
constexpr int popcnt(ll x) { return __builtin_popcountll(x); }
// [a,b]
template <class Int> Int rand(Int a, Int b) { static mt19937_64 mt{random_device{}()}; return uniform_int_distribution<Int>(a,b)(mt); }
i64 irand(i64 a, i64 b) { return rand<i64>(a,b); }
u64 urand(u64 a, u64 b) { return rand<u64>(a,b); }
// <<<
// >>> LCA

constexpr int dst(int v) { return v; }
template <class E, class = decltype(declval<E>().to)>
constexpr int dst(E const& e) { return e.to; }

template <class E> struct LCA {
    vector<vector<E>> const* g;
    int32_t n,lg,root;
    vector<int32_t> d;
    vector<vector<int32_t>> anc;
    LCA() {}
    LCA(vector<vector<E>> const* g, int root)
        : g(g), n(g->size()), root(root), d(n) {
        lg = 1; while ((1<<lg) < n) lg++; // lg == 1 when n <= 1
        anc.assign(lg, vector<int32_t>(n,-1));
        dfs(root);
        rep (i,lg-1) rep (j,n) if (anc[i][j] >= 0) {
            anc[i+1][j] = anc[i][anc[i][j]];
        }
    }
    void dfs(int x, int p = -1) {
        anc[0][x] = p;
        d[x] = (p == -1 ? 0 : d[p]+1);
        for (auto const& e : (*g)[x]) if (dst(e) != p) dfs(dst(e),x);
    }
    int dep(int a) const { return d[a]; }
    int operator()(int a, int b) const { return lca(a,b); }
    int lca(int a, int b) const {
        if (d[a] > d[b]) swap(a,b);
        for (int dd = d[b]-d[a], i = 0; dd; dd >>= 1, i++) {
            if (dd&1) b = anc[i][b];
        }
        if (a == b) return a;
        for (int i = lg-1; i >= 0; i--) {
            if (anc[i][a] != anc[i][b]) a = anc[i][a], b = anc[i][b];
        }
        return anc[0][a];
    }
    int dist(int a, int b) const { return d[a] + d[b] - 2*d[lca(a,b)]; }
    int climb(int v, int dist) const {
        for (int i = 0; dist && v >= 0; dist >>= 1, i++) {
            if (dist&1) v = anc[i][v];
        }
        return v;
    }
};
template <class E>
auto get_lca(vector<vector<E>> const& g, int root = 0) { return LCA<E>(&g,root); }

// <<<

int32_t main() {
    int n, q, c; cin >> n >> q >> c;
    struct edge { int to, cost; };
    vector<vector<edge>> g(n);
    rep (i,n-1) {
        int a, b, c; cin >> a >> b >> c; --a, --b;
        g[a].pb({b, c});
        g[b].pb({a, c});
    }
    vector<int> x(q); cin >> x;
    for (auto &e : x) cin >> e, e--;

    vector<int> dep(n, INF);
    {
        queue<int> q;
        q.push(0);
        dep[0] = 0;
        while (q.size()) {
            int a = q.front(); q.pop();
            for (auto e : g[a]) {
                if (chmin(dep[e.to], dep[a] + e.cost)) {
                    q.push(e.to);
                }
            }
        }
    }

    auto lca = get_lca(g);
    auto dist = [&](int a, int b) {
        return dep[a] + dep[b] - 2*dep[lca(a, b)];
    };

    vector<int> dp(n, INF);
    dp[x[0]] = 0;
    rep (i,q-1) {
        vector<int> ndp(n, INF);

        def (dfs, int a, int p) -> int {
            chmin(ndp[a], dp[a] + c + dist(a, x[i+1]));
            for (auto e : g[a]) {
                if (e.to == p) continue;
                chmin(ndp[a], dfs(e.to, a));
            }
            return ndp[a];
        };
        dfs(x[i+1], -1);

        int min_dp = *min_element(all(dp));
        rep (j,n) {
            chmin(ndp[j], dp[j] + dist(x[i], x[i+1]));
            chmin(ndp[j], min_dp + dist(x[i], j) + dist(j, x[i+1]));
        }

        swap(dp, ndp);
    }

    cout << *min_element(all(dp)) << endl;

}