#include <bits/stdc++.h>
using namespace std;


int main()
{
	int n, m;
	cin >> n >> m;
	vector<vector<bool>> G(n+1, vector<bool>(n+1, false));

	for(int i = 0; i < m; ++i)
	{
		int u, v;
		cin >> u >> v;
		G[u][v] = true;
		G[v][u] = true;
	}
	int ans = 20;
	for(int mask = 0; mask < (1 << (n+1)); ++mask)
	{
		int cnt = 0;
		vector<vector<bool>> visited(n+1, vector<bool>(n+1, false));
		for(int i = 1; i <= n; ++i)
		{
			if(mask & (1 << i))
			{
				++cnt;
				for(int j = 1; j <= n; ++j)
				{
					if(G[i][j])
					{
						visited[i][j] = true;
						visited[j][i] = true;
					}
				}
			}
		}
		bool allVisited = true;
		for(int i = 1; i <= n; ++i)
		{
			for(int j = 1; j <= n; ++j)
			{
				if(G[i][j] && !visited[i][j])
				{
					allVisited = false;
				}
			}
		}
		if(allVisited)
			ans = (cnt < ans) ? cnt: ans;
	}

	cout << ans << endl;
	return 0;
}