#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
int main()
{
ll n,m,k,i;
cin>>n>>m>>k;
set< ll > A[n+1];
for(i=0;i<m;i++)
{
ll u,v;
cin>>u>>v;
A[u].insert(v);
A[v].insert(u);
}
ll visited[n+1];
for(i=1;i<=n;i++)
{
visited[i]=-1;
}
queue< pair< ll,ll > > q;
for(i=0;i<k;i++)
{
ll r;
cin>>r;
q.push({r,0});
visited[r]=0;
}
ll ans=-1;
bool flag=false;
while(!q.empty())
{
pair< ll,ll > m=q.front();
q.pop();
ans=m.second;
for(auto it: A[m.first])
{
if(visited[it]==-1)
{
q.push({it,m.second+1});
visited[it]=m.second+1;
A[it].erase(m.first);
}
else
{
ans=m.second;
flag=true;
break;
}
}
if(flag)
{
break;
}
}
ll sol=0;
for(i=1;i<=n;i++)
{
if(visited[i]>=0&&visited[i]<=ans)
{
sol++;
}
}
cout<<sol<<endl;
return 0;
}
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