#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define vi vector<long long>
#define all(x) x.begin(), x.end()
#define endl "\n"
#define pb push_back
#define pr pair<ll, ll>
#define ff first
#define ss second
void solution();
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
solution();
return 0;
}
const int N = 1e5+10;
const long long inf = 1e18;
vector<pr> adj[N];
ll dist[N][3];
int st[N][3];
void solution() {
memset(st, -1, sizeof(st));
for (int i = 0; i < N; i++) {
dist[i][0] = dist[i][1] = dist[i][2] = inf;
}
ll n, m, k;
cin >> n >> m >> k;
while (m--) {
ll a, b, w;
cin >> a >> b >> w;
adj[a].pb({b, w});
adj[b].pb({a, w});
}
vi v(k);
for (ll &z : v) cin >> z;
auto cal = [&](int a, int from, ll d) {
if (st[a][0] == -1) {
dist[a][0] = d;
st[a][0] = from;
} else if (st[a][1] == -1) {
dist[a][1] = d;
st[a][1] = from;
} else {
dist[a][2] = d;
st[a][2] = from;
}
};
priority_queue<array<ll, 3>> q;
// {dist, curr, from}
for (auto a : v) {
for (auto [b, w] : adj[a]) {
q.push({-w, b, a});
}
}
while (!q.empty()) {
auto [d, a, f] = q.top(); q.pop();
if (st[a][2] != -1 || f == a ||
st[a][0] == f || st[a][1] == f || st[a][2] == f) continue;
cal(a, f, -d);
for (auto [b, w] : adj[a]) {
if (st[b][0] == f || st[b][1] == f || st[b][2] == f ||
f == b || st[b][2] != -1) continue;
q.push({d-w, b, f});
}
}
auto era = [&](vi &t) {
sort(all(t));
t.erase(unique(all(t)), t.end());
};
vector<array<ll, 3>> avl;
for (auto a : v) {
if (st[a][0] != -1)
avl.pb({dist[a][0], a, st[a][0]});
if (st[a][1] != -1)
avl.pb({dist[a][1], a, st[a][1]});
if (st[2][a] != -1)
avl.pb({dist[a][2], a, st[a][2]});
}
sort(all(avl));
ll ans = inf;
for (int i = 0; i < avl.size(); i++) {
if (min(avl[i][1], avl[i][2]) != 1 &&
max(avl[i][1], avl[i][2]) != 2) {
ans = min(ans, 1 + avl[i][0]);
break;
}
}
cout << ans << endl;
return;
// for (int i = 0; i < avl.size(); i++) {
// for (int j = i+1; j < avl.size(); j++) {
// vi temp;
// temp.pb(avl[i][1]); temp.pb(avl[i][2]);
// temp.pb(avl[j][1]); temp.pb(avl[j][2]);
// era(temp);
// if (temp.size() == 4) {
// ans = min(ans, avl[i][0] + avl[j][0]);
// }
// }
// }
// cout << ans << endl;
}
