#include <bits/stdc++.h>

using namespace std;

int ans;
int vis[510];
vector<int> E[510];
vector<int> G[50];
stack<int> D;

void dfs(int u, int s)
{
	if (s >= ans) return;
	if (u > 30) {
		ans = min(ans, s);
		return;
	}
	int tag = 1;
	for (int i = 0; i < E[u].size(); i++) {
		int v = E[u][i];
		tag &= vis[v];
	}
	if (tag || vis[u]) {
		dfs(u + 1, s);
		return;
	}
	vis[u] = 1;
	D.push(u);
	dfs(u + 1, s + 1);
	D.pop();
	vis[u] = 0;

	int delta = 0;
	G[u].clear();
	for (int i = 0; i < E[u].size(); i++) {
		int v = E[u][i];
		if (!vis[v]) {
			vis[v] = 1;
			G[u].push_back(v);
			delta++;
			D.push(v);
		}
	}
	dfs(u + 1, s + delta);
	for (int i = 0; i < G[u].size(); i++) {
		int v = G[u][i];
		vis[v] = 0;
		D.pop();
	}
}

int main()
{
	int n, m;
	while (scanf("%d%d", &n, &m) != EOF) {
		for (int i = 1; i <= n; i++) {
			E[i].clear();
			vis[i] = 0;
		}
		for (int i = 0; i < m; i++) {
			int u, v;
			scanf("%d%d", &u, &v);
			E[u].push_back(v);
			E[v].push_back(u);
		}
		ans = m;
		dfs(1, 0);
		printf("%d\n", ans);
	}
	return 0;
}