#include <bits/stdc++.h>
using namespace std;
// #define int long long
// #define double long double
#define rep(i,a,b) for (int i=(int)(a); i<(int)(b); ++i)
#define repeq(i,a,b) for (int i=(int)(a); i<=(int)(b); ++i)
#define rrep(i,a,b) for (int i=(int)(a)-1; i>=(int)(b); --i)
#define rrepeq(i,a,b) for (int i=(int)(a); i>=(int)(b); --i)
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
using ll = long long;
using vi = vector<int>;
using vl = vector<ll>;
using vb = vector<bool>;
template<typename T> using Graph = vector<vector<T>>;
template<typename T> using Spacial = vector<vector<vector<T>>>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template<typename T> using greater_priority_queue = priority_queue<T, vector<T>, greater<T>>;
const int MOD = 1e9+7;
const int MOD2 = 998244353;
// const double EPS = 1e-9;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
string interval[2] = {" ", "\n"}; // {" ", "\n"}

template<typename T> struct is_plural : false_type{};
template<typename T1, typename T2> struct is_plural<pair<T1, T2>> : true_type{};
template<typename T> struct is_plural<vector<T>> : true_type{};
template<typename T> struct is_plural<complex<T>> : true_type{};
template<> struct is_plural<string> : true_type{};

template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p) { return is >> p.first >> p.second; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p) { return os << p.first << " " << p.second; }
template<typename T> istream &operator>>(istream &is, vector<T> &vec) { for (auto itr = vec.begin(); itr != vec.end(); ++itr) is >> *itr; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec) { if (vec.empty()) return os; bool pl = is_plural<T>(); os << vec.front(); for (auto itr = ++vec.begin(); itr != vec.end(); ++itr) os << interval[pl] << *itr; return os; }

bool CoutYN(bool a, string y = "Yes", string n = "No") { cout << (a ? y : n) << "\n"; return a; }

template<typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template<typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

long long modpow(int a, long long n, int mod = MOD) { long long ret = 1; do { if (n & 1) ret = ret * a % mod; a = 1LL * a * a % mod; } while (n >>= 1); return ret; }

template<typename T> T GCD(T a, T b) { return b ? GCD(b, a%b) : a; }
template<typename T> T LCM(T a, T b) { return a / GCD(a, b) * b; }

template<typename T1, typename T2> bool CompareBySecond(pair<T1, T2> a, pair<T1, T2> b) { return a.second != b.second ? a.second < b.second : a.first < b.first; }
template<typename T1, typename T2> bool CompareByInverse(pair<T1, T2> a, pair<T1, T2> b) { return a.first != b.first ? a.first < b.first : a.second > b.second; }


/* -------- <templates end> -------- */


template<typename T>
struct edge {
  int from, to;
  T cost;

  edge(int to, T cost) : from(-1), to(to), cost(cost) {}

  edge(int from, int to, T cost) : from(from), to(to), cost(cost) {}

  operator int() const { return to; }

  bool operator<(const edge<T> &e) const {
    return cost < e.cost;
  }
};

template<typename T> using Edges = vector<edge<T>>;
template<typename T> using WeightedGraph = vector<vector<edge<T>>>;

void solve() {
  int n, m; cin >> n >> m;
  vb dead(n, false);
  Graph<int> cnt(n, vi(n, -1));
  WeightedGraph<int> g(n);
  rep(i,0,m) {
    int x, y; cin >> x >> y; --x, --y;
    if (++cnt[x][y]) dead[x] = dead[y] = true;
    if (cnt[x][y] < 2) {
      g[x].emplace_back(y, i);
      g[y].emplace_back(x, i);
    }
  }

  int ans = 0;

  rep(i,0,n) {
    if (dead[i]) continue;
    vb base(n, false);
    set<edge<int>, greater<edge<int>>> tmp;
    tmp.emplace(i, m);
    while (!tmp.empty()) {
      auto e = *begin(tmp); tmp.erase(tmp.begin());
      auto itr = lower_bound(ALL(g[e.to]), e);
      while (itr != g[e.to].begin()) {
        if (base[(--itr)->to]) {
          base[i] = true;
          break;
        }
        base[itr->to] = true;
        tmp.emplace(*itr);
      }
      if (base[i]) break;
    }
    if (base[i]) continue;
    base[i] = true;

    rep(j,i+1,n) {
      if (dead[j] || base[j]) continue;
      vb seen = base;
      set<edge<int>, greater<edge<int>>> s;
      s.emplace(j, m);
      while (!s.empty()) {
        auto e = *begin(s); s.erase(s.begin());
        auto itr = lower_bound(ALL(g[e.to]), e);
        while (itr != g[e.to].begin()) {
          if (seen[(--itr)->to]) {
            seen[j] = true;
            break;
          }
          seen[itr->to] = true;
          s.emplace(*itr);
        }
        if (seen[j]) break;
      }
      if (!seen[j]) ++ans;
    }
  }

  cout << ans << endl;
}


/* -------- <programs end> -------- */


signed main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(10);
  solve();
  return 0;
}


Measured memory_bytes: 6724