#include <iostream>
#include <algorithm> // for sort, mainly
#include <vector>
#include <map>
#include <set>
#include <cmath>
#include <array>
#include <string>
#include <cstdio>
#include <iterator>
#include <unordered_set>
#include <cstdint> // for int64_t, int32_t, etc
#include <queue>
#include <stack>
#include <deque>
#include <numeric> // gcd, lcm
#include <fstream>
#include <bitset> // for bitset
#include <iomanip>
#include <cassert> // for set with custom ordering
#include <type_traits> // for set with custom ordering
#include <utility> // for swap, forward, etc
using namespace std;

#pragma GCC optimize("O2")
// #pragma GCC optimize("O1","O2","O3","Ofast","unroll-loops")
// #pragma GCC target("sse","sse2","sse3","sse4.1","sse4.2","avx","avx2","fma")

template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
void dbg_out() { cout << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cout << ' ' << H; dbg_out(T...); }
#ifdef LOCAL
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif

/*

notes:

int64_t
stoi(string s) -> string to int
to_string() -> int (or else) to string

vector declaration:
vector<ll> v(n, 0)
vector<vector<ll>> v(n, vector<ll>(n, 0));

{if statement} ? {truth value} : {false value}

#ifdef LOCAL
    freopen("in.txt","r",stdin);
    freopen("out.txt","w",stdout);
#endif

std::lcm(ll a, ll b), std::gcd(int a, int b)

cout << fixed << setprecision(n);

set with custom ordering
set<ll, decltype(&cmp)> qu(cmp);

*/

typedef int64_t ll;

ll n, m, k;

vector<vector<ll>> out;
vector<vector<ll>> in;

vector<ll> ord;
vector<ll> comp;

void dfs1(ll curr, vector<bool> &vis) {

	for(const auto & x : out[curr]) {
		if(vis[x] == false) {
			vis[x] = true;
			dfs1(x, vis);
		}
	}

	ord.push_back(curr);

}

void dfs2(ll curr, vector<bool> &vis, ll currcomp) {

	for(const auto & x : in[curr]) {
		if(vis[x] == false) {
			vis[x] = true;
			dfs2(x, vis, currcomp);
		}
	}

	comp[curr] = currcomp;

}

void solve() {

	cin >> n >> m >> k;

	//cerr << "\nn=" << n << "; m=" << m << "; k=" << k;

	out.resize(n+1);
	in.resize(n+1);
	comp.resize(n+1);

	for(ll i = 0; i < m; i++) {
		ll a, b;
		cin >> a >> b;
		out[a].push_back(b);
		in[b].push_back(a);
	}

    vector<bool> heretok(n+1, false);

    heretok[k] = true;

	queue<ll> q;
    q.push(k);
    vector<bool> b(n+1, false);
    while(!q.empty()) {

        ll curr = q.front();
        q.pop();

        heretok[curr] = true;

        for(const auto & x : in[curr]) {

            if(b[x] == false) {
                b[x] = true;
                q.push(x);
            }

        }

    }

    vector<bool> res(n+1, false);
    q.push(k);
    res[k] = true;
    b.clear();
    b.resize(n+1, false);
    b[k] = true;
    while(!q.empty()) {

        ll curr = q.front();
        q.pop();

        res[curr] = true;

        bool midp = heretok[curr];

        //cerr << "\ncurr=" << curr;
        //cerr << "\nmidp=" << midp;

        for(const auto & x : out[curr]) {

            if(midp) {
                res[x] = true;
            }

            if(b[x] == false && midp) {

                b[x] = true;
                q.push(x);
            }
        }

    }

    ll resc = 0;
	for(ll i = 1; i <= n; i++) {
        if(i == k) { continue; }
		resc += res[i];
	}

	cout << resc << "\n";
	for(ll i = 1; i <= n; i++) {
        if(i == k) { continue; }
		if(res[i]) {
			cout << i << " ";
		}
	}

}

int main()
{
	std::ios_base::sync_with_stdio(false);
	//cin.tie(nullptr);
	//cout.tie(nullptr);

	solve();

	return 0;
}