#include<stdio.h>
#include<vector>
#include<queue>
using namespace std;

#define MAX_N 2001
#define mp make_pair
#define INF 9999999

int n,m,k,prieteni[MAX_N],d[MAX_N],t[MAX_N];
vector < pair<int,int> > gr[MAX_N];

void read(void)
{
	freopen("ubuntzei.in","r",stdin);
	int i,x,y,c;
	scanf("%d %d %d",&n,&m,&k);
	for(i=1; i<=k; i++)
		scanf("%d",&prieteni[i]);
	
	for(i=1; i<=m; i++)
	{
		scanf("%d %d %d",&x,&y,&c);
		gr[x].push_back(mp(y,c));
		gr[y].push_back(mp(x,c));
	}
}

void bellman_ford(int start)
{
	int i,x;  queue<int> C;
	vector < pair<int,int> > ::iterator it;
	for(i=2; i<=n; i++)
		d[i]=INF;   
	C.push(start);
	while(!C.empty())
	{
		x=C.front();
		C.pop();
		
		for(it=gr[x].begin(); it!=gr[x].end(); it++)
			if(d[it->first]>d[x]+it->second)
			{
				d[it->first]=d[x]+it->second;
				t[it->first]=x;
				C.push(it->first);
			}
	}
}

void build_path(int &cnt,int nod)
{
	if(t[nod])
		build_path(cnt,t[nod]);
	cnt++;
}

void write(void)
{
	int cnt=0;
	freopen("ubuntzei.out","w",stdout);
	build_path(cnt,n);
	printf("%d",cnt);
}
	

int main()
{
	read();
	bellman_ford(1);
	write();
	return 0;
}