#include <bits/stdc++.h>

using namespace std;
int n,m,k,dist[2003][2003],dp[(1<<16)+1],root,nod,v[2003];vector < pair <int,int> > graf[2003];
priority_queue < pair <int,int> , vector < pair <int,int> > , greater < pair <int,int> > > chestie;
void dijkstra () {
	while(!chestie.empty()) {
		nod=chestie.top().second;chestie.pop();
		for(int i=0;i<(int)graf[nod].size();++i)
			if(dist[root][graf[nod][i].first]>dist[root][nod]+graf[nod][i].second) {
				dist[root][graf[nod][i].first]=dist[root][nod]+graf[nod][i].second;
				chestie.push({dist[root][graf[nod][i].first],graf[nod][i].first});
			}
	}
}
int main () {
	int nr,nr1,nr2;
	freopen("ubuntzei.in","r",stdin);
	freopen("ubuntzei.out","w",stdout);
	scanf("%d%d%d", &n, &m, &k);
	for(int i=1;i<=k;++i)
		scanf("%d", &nr),v[nr]=i;
	for(int i=1;i<=m;++i)
		scanf("%d%d%d", &nr, &nr1, &nr2),graf[nr].push_back({nr1,nr2}),graf[nr1].push_back({nr,nr2});
	memset(dist,0x3f3f,sizeof(dist));
	for(int i=1;i<=n;++i) {
		root=i;chestie.push({0,i});dist[i][i]=0;dijkstra();
	}
	memset(dp,0x3f3f,sizeof(dp));dp[0]=0;
	printf("-1");
	return 0;
}