#include<bits/stdc++.h>
using namespace std;

vector<vector<int>> g, gr;
vector<bool> vis, visr;
vector<bool> ans;

void dfs(int v){
    vis[v] = true;
    for(int x : g[v]){
        if(!vis[x]) dfs(x);
    }
}

void dfsr(int v){
    visr[v] = true;
    for(int x : gr[v]){
        if(!visr[x]) dfsr(x);
    }
}

int main(){
    int n, m, k; cin >> n >> m >> k;
    g.resize(n+1);
    gr.resize(n+1);
    for(int i=0; i<m; i++){
        int u, v; cin >> u >> v;
        g[u].push_back(v);
        gr[v].push_back(u);
    }
    vis.resize(n+1, 0);
    dfs(k);
    visr.resize(n+1, 0);
    dfsr(k);
    //for(bool x : vis) cout << x << " "; cout << endl;
    //for(bool x : visr) cout << x << " "; cout << endl;
    ans.resize(n+1, 0);
    for(int i=1; i<=n; i++){
        if(vis[i] && visr[i]){
            ans[i] = true;
            for(int x : g[i]){
                ans[x] = true;
            }
        }
    }
    ans[k]=false;
    int db=0;
    for(bool x : ans) if(x) db++;
    cout << db << endl;
    for(int i=1; i<=n; i++){
        if(ans[i]) cout << i << " ";
    }
    cout << endl;
}