#include <bits/stdc++.h>

using namespace std;

void dfs2(int curr, vector<vector<int>>& e, vector<bool>& visited, vector<bool>& pathnode, vector<int>& solutions) {
    for (int s : e[curr]) {
        if (!visited[s]) {
            visited[s] = true;
            solutions.push_back(s);
            if (pathnode[s]) dfs2(s, e, visited, pathnode, solutions);
        }
    }
}

int main()
{
    int n, m, k; cin >> n >> m >> k;
    vector<vector<int>> e(n + 1, vector<int>(0));
    vector<vector<int>> visszae(n + 1, vector<int>(0));
    vector<int> solutions(0);
    for (int i = 0; i < m; i++) {
        int u, v; cin >> u >> v;
        e[u].push_back(v);
		visszae[v].push_back(u);
    }
    vector<bool> pathnode(n, false);
    
	queue<int> q;
	q.push(k);
	while(!q.empty()) {
		int curr = q.front(); q.pop();
		for (int s : visszae[curr]) {
			if (!pathnode[s]) {
				q.push(s);
				pathnode[s] = true;
			}
		}
	}

    vector<bool> visited(n, false);
    visited[k] = true;
    dfs2(k, e, visited, pathnode, solutions);

    if (solutions.size() == 0) cout << 0;
    else {
       cout << solutions.size() << '\n';
        for (int s : solutions) {
            cout << s << ' ';
        }
    }
}