#include <iostream>
#include <vector>
#include <deque>

using namespace std;

#define f(l,j,k) for (int i = l; i <= j; i = i + k)

struct csp
{
    bool lat;
    int lep;
    vector<int> sz;
};

int n, m, k, c, a, akt, s;


vector<int> ism;
vector<int> meg;

vector<csp> x;
deque<int> v;

void bejar(vector<csp> x, int a, int b, int c)
{
    int kezd = c;
    v.push_back(kezd);
    x[kezd].lat = true;
    x[kezd].lep = 1;

    while (!v.empty())
    {
        akt = v.front();
        v.pop_front();
        for (auto& e : x[akt].sz)
        {
            if (!x[e].lat)
            {
                v.push_back(e);
                x[e].lat = 1;
                x[e].lep = x[akt].lep + 1;
            }
        }
    }
    if (abs(x[a].lep - x[b].lep) <= 1)
    {
        meg.push_back(c);
        s++;
    }
}


int main()
{
    cin >> n >> m >> k;

    x.resize(n + 1);
    
    f(1, k, 1)
    {
        cin >> c;
        ism.push_back(c);
    }

    f(1, m, 1)
    {
        cin >> a >> c;
        x[a].sz.push_back(c);
        x[c].sz.push_back(a);
    }

    f(1, n, 1)
    {
        bejar(x, ism[0], ism[1], i);
    }
    
    cout << s << endl;

    for (auto& e : meg)
        cout << e << " ";

   
}