#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int N, M, K;
    cin >> N  >> M >> K;
    K--;

    vector<vector<int>> et(N); // ?edge to
    vector<vector<int>> ef(N); // ?edge from
    vector<bool> rh(N); // ?reach home
    vector<bool> ty(N); // ?temporary


    int U, V;
    for(int _=0; _<M; _++){
        cin >> U >> V;
        U--; V--;
        et[U].push_back(V);
        ef[V].push_back(U);
    }




    vector<int> Q;
    Q.push_back(K);
    int si = 0; // start index
    ty[K] = true;
    while(si < Q.size()){
        for(int n : ef[Q[si]]){
            if(!ty[n]){
                ty[n] = true;
                rh[n] = true;
                Q.push_back(n);
            }
        }
        si++;
    }




    Q.clear();
    Q.push_back(K);
    si = 0;
    int oc = 0;
    vector<int> ol;
    for(int i=0; i<N; i++) ty[i] = false;
    ty[K] = true;
    while(si < Q.size()){
        for(int n : et[Q[si]]){
            if(!ty[n]){
                ty[n] = true;
                oc++;
                ol.push_back(n);
                if(rh[n])
                    Q.push_back(n);
            }
        }
        si++;
    }

    cout << oc << endl;
    for(int &dv : ol) cout << dv+1 << " ";
    cout << endl;

    return 0;
}