#include "bits/stdc++.h"
#include <algorithm>
#include <random>

using namespace std;

using ll = long long;
using pii = pair<int, int>;


void encode() {

}

void decode() {

}

int mnmx = 1e9;
int mxmx = 0;
int mnmn = 1e9;
int mxmn = 0;

const int N = 1001;
vector<int> G[N];
set<pii> S;

bool has[N][N];
bool exist(int u, int v){
	return has[u][v] || has[v][u];
}

#define forn(i, j, k) for(int i = j; i < k; i++)
void test(int t) {

	for(auto [u, v] : S){
		G[u].push_back(v);
		G[v].push_back(u);
		has[u][v] = has[v][u] = 1;
	}

	bool success = false;
	for(int v = 1; v <= 1000; v++){
		int sz = G[v].size();
		forn(i, 0, sz) forn(j, i + 1, sz) forn(k, j + 1, sz) forn(l, k + 1, sz) {
			vector<int> adj {i, j, k, l};
			bool ok = true;
			for(int x = 0; x < 4; x++) {
				for (int y = x + 1; y < 4; y++){
					ok &= exist(adj[x], adj[y]);
				}
			}
			if(ok){
				cout << "ok" << endl;
				return;
			}
		}
	}

	int cnt = 0;
	for(int v = 1; v <= 1000; v++){
		int sz = G[v].size();
		forn(i, 0, sz) forn(j, i + 1, sz) forn(k, j + 1, sz) forn(l, k + 1, sz) {
			vector<int> adj {G[v][i], G[v][j], G[v][k], G[v][l]};
			for(int x = 0; x < 4; x++) {
				for (int y = x + 1; y < 4; y++){
					int u = adj[x], v = adj[y];
					cnt++;
					if(exist(u, v)){
						cout << "mark" << '\n';
						vector<pair<int, int>> ans;
						for(int a = 0; a < 4; a++){
							for(int b = a + 1; b < 4; b++){
								if(!exist(adj[a], adj[b])){
									ans.push_back({adj[a], adj[b]});
								}
							}
						}
						cout << ans.size() << '\n';
						for(auto [x, y] : ans){
							cout << x << ' ' << y << '\n';
						}
						return;
					}
				}
			}
		}
	}
	cout << cnt << endl;
	assert(false);
}
 
int32_t main() {
	cin.tie(0)->sync_with_stdio(0);
	cout << fixed << setprecision(10);

	int n, m; cin >> n >> m;
	for(int i = 0; i < m; i++){
		int u, v; cin >> u >> v;
		G[u].push_back(v);
		G[v].push_back(u);
		has[u][v] = has[v][u] = true;
	}	
	test(1);
}