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

int main(){
    cin.tie(0);
    int n,m,k; cin >> n >> m >> k;
    vector< vector<int> > graf1(n);
    vector< vector<int> > graf2(n);
    for (int i=0;i<m;i++){
        int u,v; cin >> u >> v;
        graf1[u-1].push_back(v-1);
        graf2[v-1].push_back(u-1);
    }
    int c=0;
    vector<int> ki;
    queue<int> Q;
    Q.push(k-1);
    vector<int> szin(n,0);
    vector<int> szin2(n,0);
    while(!Q.empty()){
        int u=Q.front();
        Q.pop();
        for (int v:graf1[u]){
            if (szin2[v]==0){
                c++;ki.push_back(v+1);szin2[v]=1;
            }
        }
        for (int v:graf2[u]){
            if (szin[v]==0){Q.push(v);}
        }
        szin[u]=1;
    }
    cout << c-1 << "\n";
    for(int i=0;i<c;i++){if(ki[i]!=k){cout << ki[i] << " ";};}
}