#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> p32;
typedef pair<ll,ll> p64;
typedef pair<double,double> pdd;
typedef vector<ll> v64;
typedef vector<int> v32;
typedef vector<vector<int> > vv32;
typedef vector<vector<ll> > vv64;
typedef vector<vector<p64> > vvp64;
typedef vector<p64> vp64;
typedef vector<p32> vp32;
double eps = 1e-12;
#define forn(i,e) for(ll i = 0; i < e; i++)
#define forsn(i,s,e) for(ll i = s; i < e; i++)
#define rforn(i,s) for(ll i = s; i >= 0; i--)
#define rforsn(i,s,e) for(ll i = s; i >= e; i--)
#define ln "\n"
#define dbg(x) cout<<#x<<" = "<<x<<ln
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define INF 2e18
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())
ll MOD = 1e9 + 7;
int N_MAX = 1e4;
vector<vector<int>> e1(N_MAX + 1), e2(N_MAX + 1);
vector<bool> reachK(N_MAX + 1);
vector<bool> visited(N_MAX + 1);
vector<int> ans;
int n, m, k;
void dfs(int x){
reachK[x] = 1;
for(int i = 0; i < e2[x].size(); i++){
if(!reachK[e2[x][i]]){
dfs(e2[x][i]);
}
}
}
void dfs2(int x){
visited[x] = 1;
if(x != k) ans.push_back(x);
for(int i = 0; i < e1[x].size(); i++){
if(!visited[e1[x][i]] && (reachK[e1[x][i]] || reachK[x])){
dfs2(e1[x][i]);
}
}
}
int main()
{
//ifstream cin("in.txt");
cin >> n >> m >> k;
for(int i = 1; i <= m; i++){
int a, b;
cin >> a >> b;
e1[a].push_back(b);
e2[b].push_back(a);
}
dfs(k);
dfs2(k);
cout << ans.size() << '\n';
for(int a:ans){
cout << a << " ";
}
}