#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
struct Data{
int u,tot,src;
Data(){};
Data(int _u,int _tot,int _src){
u = _u;
tot = _tot;
src = _src;
}
bool operator <(const Data &b) const{
return b.tot > this->tot;
}
};
struct comp{
bool operator()(Data &a,Data &b) const{
return b.tot < a.tot;
}
};
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
const int inf = 1e9 + 5;
int n,m,k;
cin >> n >> m >> k;
vector<vector<pair<int,int>>> adj(n);
for(int i = 0;i < m;i++){
int u,v,w;
cin >> u >> v >> w;
u --;
v --;
adj[u].emplace_back(v,w);
adj[v].emplace_back(u,w);
}
vector<multiset<pair<int,int>>> dist(n);
priority_queue<Data,vector<Data>,comp> pq;
int lm = 2;
for(int i = 0;i < n;i++){
for(int j = 0;j < lm;j++){
dist[i].insert({inf,-1});
}
}
vector<int> s(k);
for(int i = 0;i < k;i++){
cin >> s[i];
s[i] --;
if(s[i] == 0 || s[i] == 1) continue;
pq.push(Data(s[i],0,s[i]));
}
while(!pq.empty()){
Data d = pq.top();
pq.pop();
int u = d.u;
int tot = d.tot;
int src = d.src;
if(prev(dist[u].end())->first < tot) continue;
bool ok = true;
for(auto &p : dist[u]){
if(p.second == src){
ok = false;
assert(p.first <= tot);
break;
}
}
if(!ok) continue;
dist[u].erase(prev(dist[u].end()));
dist[u].insert({tot,src});
for(auto &p : adj[u]){
int v = p.first;
int w = p.second;
if(prev(dist[v].end())->first > tot + w){
pq.push(Data(v,tot + w,src));
}
}
}
int ans = inf;
for(int i = 0;i < k;i++){
ans = min(ans,next(dist[s[i]].begin())->first);
}
cout << ans + 1 << '\n';
return 0;
}
