#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define pf push_front
#define mp make_pair
#define fi first
#define se second
#define int long long
#define all(x) (x).begin(), (x).end()
typedef long double ld;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<bool>> vvb;
typedef vector<vector<ll>> vvll;
typedef vector<string> vs;
typedef vector<vector<string>> vvs;
typedef vector<char> vc;
typedef vector<vector<char>> vvc;
typedef map<int, int> mii;
typedef unordered_map<int, int> umii;
const int mod = 1e9 + 7;
const int inf = INTMAX_MAX;
const bool tc = false;
int n, m, k;
vector<vector<pii>> adj; set<int> sp;
int dijkstra(int s, vi & d, vector<vector<pii>> & adj) {
int n = adj.size();
d.assign(n, inf);
d[s] = 0;
set<pll> q;
q.insert({0, s}); int ans = -1;
while (!q.empty()) {
int v = q.begin()->second;
q.erase(q.begin());
if ((sp.find(v) != sp.end()) && v != s) {
ans = v;
break;
}
for (auto edge : adj[v]) {
int to = edge.first;
int len = edge.second;
if (d[v] + len < d[to]) {
q.erase({d[to], to});
d[to] = d[v] + len;
q.insert({d[to], to});
}
}
}
return ans;
}
class DisjointSets {
private:
vector<int> parents;
vector<int> sizes;
public:
DisjointSets(int size) : parents(size), sizes(size, 1) {
for (int i = 0; i < size; i++) { parents[i] = i; }
}
int find(int x) {
return parents[x] == x ? x : (parents[x] = find(parents[x]));
}
bool unite(int x, int y) {
int x_root = find(x);
int y_root = find(y);
if (x_root == y_root) { return false; }
if (sizes[x_root] < sizes[y_root]) { swap(x_root, y_root); }
sizes[x_root] += sizes[y_root];
parents[y_root] = x_root;
return true;
}
bool connected(int x, int y) { return find(x) == find(y); }
};
void dfs(int node, set<int> & comps, vi & vis) {
vis[node] = 1;
if (sp.find(node) != sp.end()) comps.insert(node);
for (auto &neighbour : adj[node]) {
if (vis[neighbour.fi]) continue;
dfs(neighbour.fi, comps, vis);
}
}
int solve(int x) {
set<int> comps; vi vis(n); dfs(x, comps, vis); int ans = 1e18;
for (auto it = comps.begin(); it != comps.end(); it++) {
int u = *it;
vi d(n); int v = dijkstra(u, d, adj);
ans = min(ans, d[v]);
}
return ans;
}
inline void solve() {
cin >> n >> m >> k;
DisjointSets dsu(n); adj.resize(n);
for (int i = 0; i < m; i++) {
int u, v, w;
cin >> u >> v >> w;
u--; v--;
adj[u].pb({v, w});
adj[v].pb({u, w});
dsu.unite(u, v);
}
for (int i = 0; i < k; i++) {
int x; cin >> x; x--;
sp.insert(x);
}
int ans = 1e18;
mii solved;
for (int i = 2; i < n; i++) {
int x = dsu.find(i);
if (solved[x]) continue;
ans = min(ans, solve(x));
solved[x] = 1;
}
cout << 1 + ans << '\n';
}
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
signed main() {
ios::sync_with_stdio(false);
cout.tie(0);
cin.tie(0);
//setIO();
int t = 1;
if (tc) {
cin >> t;
}
while (t--) {
solve();
}
}
