#include <vector>
#include <iostream>
using namespace std;
int main()
{
    int n, m, k;
    cin >> n >> m >> k;
    vector<vector<int>> innen(n + 1);
    vector<vector<int>> ide(n + 1);
    for (int i = 0; i < m; i++) {
        int e, m;
        cin >> e >> m;
        innen[e].push_back(m);
        ide[m].push_back(e);
    }
    vector<int> valasz = innen[k];
    vector<int> vizsg = ide[k];
    vector<bool> vvolt(n + 1);
    vector<bool> volt(n + 1);
    for (int x : valasz) volt[x] = true;
    volt[k] = true;
    while (vizsg.size() != 0) {
        vvolt[vizsg[0]] = true;
        for (int x : innen[vizsg[0]]) {
            if (!volt[x]) {
                valasz.push_back(x);
                volt[x] = true;
            }
        }
        for (int x : ide[vizsg[0]]) {
            if (!vvolt[x]) {                
                vizsg.push_back(x);
            }
        }
        vizsg.erase(vizsg.begin());
    }
    cout << valasz.size() << endl;
    for (int x : valasz) cout << x << " ";
}