#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <charconv>
#include <cstring>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <limits>
#include <map>
#include <optional>
#include <random>
#include <set>
#include <stdexcept>
#include <string>
#include <string_view>
#include <type_traits>
#include <unordered_map>
#include <utility>
#include <variant>
#include <vector>
#include <queue>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> ii;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<ii> vii;

#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define rep(i,a,b) for(auto i=(a); i<(b); ++i)
#define REP(i,n) rep(i,0,n)
#define all(v) (v).begin(), (v).end()
#define rs resize
#define DBG(x) cerr << __LINE__ << ": " << #x << " = " << (x) << endl

const ld PI = acos(-1.0);
template<class T> using min_queue =
priority_queue<T, vector<T>, greater<T>>;
template<class T> int sz(const T &x) {
    return (int) x.size(); // copy the ampersand(&)!
}

// START OF ACTUAL PROGRAM, START READING HERE

vvi adj;
vi deg;

bool bf(vi& A, ll i, vi R, ll c) {
	if (c == 0) {
		cout << R.size() << endl;
		for (int j = 0; j < R.size(); j++) {
			cout << R[j]+1 << (j == R.size() - 1 ? "\n" : " ");
		}
		return true;
	}
	if (i == A.size()) {
		return false;
	}
	ll d = deg[A[i]];
	for (ll r : R) {
		d -= adj[r][A[i]];
	}
	if (d > 0 && d <= c) {
		R.pb(A[i]);
		if (bf(A, i+1, R, c-d)) return true;
		R.pop_back();
	}
	if (bf(A, i+1, R, c)) return true;
	return false;
}

void run() {
	ll n, m, k;
	cin >> n >> m >> k;
	adj = vvi(n, vi(n, 0));
	deg = vi(n, 0);
	for (ll i = 0; i < m; i++) {
		ll a, b;
		cin >> a >> b;
		adj[a-1][b-1]++;
		adj[b-1][a-1]++;
		deg[a-1]++;
		deg[b-1]++;
	}

	// Collect low degree vertices
	vvi A(k+1);
	for (ll i = 0; i < n; i++) {
		if (deg[i] <= k) A[deg[i]].pb(i);
	}

	if (k == 5 && A[1].size() == 0 && A[3].size() == 0 && A[4].size() == 0 && A[5].size() == 0) {
		bool pos = false;
		for (ll i = 0; i < n; i++) {
			if (pos || (deg[i]%2 == 1 && deg[i] <= 5)) {
				pos = true;
				break;
			}
			for (ll j = i+1; j < n; j++) {
				ll a = deg[i] + deg[j] - adj[i][j];
				if (a%2 == 1 && a <= 5) {
					pos = true;
					break;
				}
			}
		}
		if (!pos) {
			cout << "impossible" << endl;
			return;
		}
	}

	// Brute force the remainder
	vi B, R;
	for (ll i = k; i >= 1; i--) {
		for (ll a : A[i]) {
			B.pb(a);
		}
	}
	if (!bf(B, 0, R, k)) {
		cout << "impossible" << endl;
	}
}

signed main() {
    // DON'T MIX "scanf" and "cin"!
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout << fixed << setprecision(20);
    run();
    return 0;
}