#include <bits/stdc++.h>
using namespace std;
template <typename T>
void view(T e) {
  std::cout << e << std::endl;
}
template <typename T>
void view(const std::vector<T>& v) {
  for (const auto& e : v) {
    std::cout << e << " ";
  }
  std::cout << std::endl;
}
template <typename T>
void view(const std::vector<std::vector<T> >& vv) {
  for (const auto& v : vv) {
    view(v);
  }
}
template <class T>
bool chmax(T& a, const T& b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T& a, const T& b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
const int MOD = 1000000007;
const int INF = 1e9;
const int mod = 1000000007;
const int inf = 1e9;
int dx[4] = {1, -1, 0, 0};
int dy[4] = {0, 0, 1, -1};
int ddx[8] = {1, 1, 1, -1, -1, -1, 0, 0};
int ddy[8] = {0, 1, -1, 0, 1, -1, 1, -1};
int main() {
  int n, m;
  cin >> n >> m;
  bool t[n][n];
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      if (i == j)
        t[i][j] = true;
      else
        t[i][j] = false;
    }
  }
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    a--, b--;
    t[a][b] = true;
    t[b][a] = true;
  }
  int ans = 1;
  for (int bit = 0; bit < 1 << n; bit++) {
    int cnt = 0;
    vector<int> can;
    for (int i = 0; i < n; i++) {
      if (1 & bit >> i) cnt++, can.push_back(i);
    }
    bool ok = true;
    for (int i = 0; i < (int)can.size(); i++) {
      for (int j = 0; j < (int)can.size(); j++) {
        if (can[i] == can[j]) continue;
        if (!t[can[i]][can[j]]) ok = false;
      }
    }
    if (ok) {
      chmax(ans, cnt);
    }
  }
  cout << ans << endl;
}
