#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
struct pont{vector<int>kim,bem; bool van=0,jo=0;};
bool has(int a, int b) {
    return a<b;}
int main()
{
    int n,m,k,x,y;
    cin>>n>>m>>k; pont a[n+1];
    for(int i=0; i<m; i++){
        cin>>x>>y; a[x].kim.push_back(y);
        a[y].bem.push_back(x);}
    vector<int>l1,l2,l3; l1.push_back(k);
    bool nincs=0; a[k].van=1;
    while(nincs==0){
        for(int i=0; i<l1.size(); i++){
            for(int j=0; j<a[l1[i]].bem.size(); j++){
                if(a[a[l1[i]].bem[j]].van==0)
                    {a[a[l1[i]].bem[j]].van=1;
                    a[a[l1[i]].bem[j]].jo=1;
                    l2.push_back(a[l1[i]].bem[j]);}}}
        if(l2.size()==0)nincs=1;
        l1.clear();
        for(int i=0; i<l2.size(); i++){l1.push_back(l2[i]);} l2.clear();}
    l1.clear(); l2.clear(); nincs=0; l1.push_back(k);
    for(int i=1; i<=n; i++){a[i].van=0;} a[k].van=1;
    while(nincs==0){
        for(int i=0; i<l1.size(); i++){
            for(int j=0; j<a[l1[i]].kim.size(); j++){
                if(a[a[l1[i]].kim[j]].van==0){
                    a[a[l1[i]].kim[j]].van=1;
                    l3.push_back(a[l1[i]].kim[j]);
                        if(a[a[l1[i]].kim[j]].jo==1)l2.push_back(a[l1[i]].kim[j]);}}}
        l1.clear();
        if(l2.size()==0)nincs=1;
        for(int i=0; i<l2.size(); i++){l1.push_back(l2[i]);}
        l2.clear();}
    if(l3.size()==0)cout<<"0";
    else{
        sort(l3.begin(),l3.end(),has);
        cout<<l3.size()<<endl;
        for(int i=0; i<l3.size(); i++){cout<<l3[i]<<" ";}}
    return 0;
}