#include<bits/stdc++.h>
using namespace std;
int n, m, u, v, s[15], tot, ans;
bool g[15][15];
int main() {
	cin >> n >> m;
	for (int i = 1; i <= n; i++) g[i][i] = 1;
	for (int i = 1; i <= m; i++) {
		cin >> u >> v;
		g[u][v] = g[v][u] = 1;
	}
	for (int i = 0; i < (1 << n); i++) {
		tot = 0;
		for (int j = 0; j < n; j++) if (i & (1 << j)) s[++tot] = j + 1;
		bool b = 1;
		for (int j = 1; j <= tot; j++) {
			for (int k = 1; k <= tot; k++) {
				if (!g[s[j]][s[k]]) {
					b = 0;
					break;
				}
			}
		}
		if(b) ans = max(ans, tot);
	}
	cout << ans;
	return 0;
}