// Fertőzési sorozat.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <vector>
#include <map>
#include <queue>
using namespace std;
vector<int>fertozesi_sor;
using namespace std;
bool possible(int x, int n,vector<vector<int>>adj)
{
    queue<int> q;
    q.push(x);
    vector<int>dist(n + 1, -1);
    vector<int>hany_szintenkent(n + 1, 0);
    dist[x] = 1;
    while (!q.empty())
    {
        int v = q.front();
        q.pop();
        for (auto next : adj[v])
        {
            if (dist[next] == -1)
            {
                dist[next] = dist[v] + 1;
                hany_szintenkent[dist[next]]++;
                q.push(next);
            }
        }
    }
    vector<int> sub_dists;
    for (int szemely : fertozesi_sor) {
        if (dist[szemely] == -1) return false; 
        sub_dists.push_back(dist[szemely]);
    }
    for (size_t i = 0; i < sub_dists.size() - 1; i++) {
        if (sub_dists[i + 1] < sub_dists[i]) return false; 
        if (sub_dists[i + 1] > sub_dists[i] + 1) return false; 
    }
    map<int, int> sub_counts;
    for (int d : sub_dists) {
        sub_counts[d]++;
    }

    int min_level = sub_dists.front();
    int max_level = sub_dists.back();
    for (int level = min_level + 1; level < max_level; level++) {
        if (sub_counts[level] != hany_szintenkent[level]) {
            return false;
        }
    }
    return true;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n, m,k;
    cin >> n >> m >> k;
    vector<vector<int>> adj(n+1);

    for (int i = 0; i < k; i++)
    {
        int x;
        cin >> x;
        fertozesi_sor.push_back(x);
    }
    for (int i = 0; i < m; i++)
    {
        int x, y;
        cin >> x >> y;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    vector<int> res;
    for (int i = 1; i <= n; i++)
    {
        if (possible(i,n,adj))
            res.push_back(i);
    }
    cout << res.size() << endl;
    for (auto x : res)
        cout << x << " ";
}