3 3
1 2
3 1
2 3
 2 0
 10 17
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
 2 1
1 2
 8 13
1 2
2 3
3 4
4 1
2 4
1 3
5 6
6 7
7 8
8 5
6 8
5 7
1 8
 3 2
1 2
2 3
 10 9
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
 10 40
1 3
2 6
9 10
4 6
1 2
1 8
6 10
3 6
1 4
5 7
3 8
3 9
4 5
3 7
8 9
5 9
5 6
2 3
3 4
1 6
4 8
3 10
5 10
2 8
2 10
4 7
1 10
1 7
4 10
5 8
8 10
7 9
6 8
2 7
4 9
6 9
7 8
6 7
1 5
2 9
 10 9
1 2
2 3
3 1
4 5
5 6
6 7
7 4
4 6
5 7
 1000000 0
 8 11
1 2
1 3
1 4
2 3
2 7
7 4
4 2
7 5
8 1
1 7
7 8
 9 9
1 2
2 3
3 1
4 5
5 6
6 4
7 8
8 9
9 7
 15 14
1 2
1 3
1 4
1 5
2 6
2 7
7 8
7 9
3 10
10 11
4 12
12 13
13 14
13 15
 10 17
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
1 10
2 3
2 4
2 5
2 6
2 7
2 8
2 9
2 10
 9 12
1 2
2 3
3 1
1 4
4 5
5 1
1 6
6 7
7 1
1 8
8 9
9 1
 3 1
1 2
 10 5
5 7
4 8
9 10
7 10
6 10
 15 15
1 2
1 3
1 4
1 5
2 6
2 7
7 8
7 9
3 10
10 11
4 12
12 13
13 14
13 15
15 1
 4 3
1 2
2 3
3 1
 10 30
4 9
4 6
1 2
8 10
7 8
4 7
1 8
6 7
5 6
1 5
7 9
1 7
8 9
7 10
9 10
3 9
2 7
5 7
5 9
2 8
2 9
5 8
3 10
1 6
3 6
2 10
6 8
3 4
2 5
4 5
 4 3
1 2
1 3
1 4
 4 6
1 2
2 3
3 4
4 1
1 3
2 4
 10 9
1 2
1 3
1 4
2 5
5 6
2 7
3 8
3 9
9 10
 10 10
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
10 1
 3 0
 6 6
1 2
2 3
3 1
4 5
5 6
6 4
 10 0
 9 15
1 2
2 3
3 1
1 4
4 5
5 1
1 6
6 7
7 1
1 8
8 9
9 1
2 9
7 4
2 8
 4 0
 1 0

1
 0
 43
 0
 8
 0
 84
 82
 63
 166666166667000000
 21
 30
 292
 64
 36
 0
 84
 284
 1
 37
 1
 4
 59
 50
 1
 2
 120
 28
 4
 0

#include <bits/stdc++.h>
using namespace std;
template <class T>
inline T gcd(T a, T b) {
  return !b ? a : gcd(b, a % b);
}
template <class T>
inline T lcm(T a, T b) {
  return a * (b / gcd(a, b));
}
template <class T>
inline T pwr(T n, T p) {
  return !p ? 1 : n * power(n, p - 1);
}
template <class T>
inline T dis(T a, T b, T c, T d) {
  return sqrt((a - c * a - c) + (b - d * b - d));
}
int on(int n, int pos) { return n = n | (1 << pos); }
int off(int n, int pos) { return n = n & ~(1 << pos); }
int check(int n, int pos) { return n & (1 << pos); }
int toggle(int n, int pos) { return check(n, pos) ? off(n, pos) : on(n, pos); }
int isupper(char c) { return (c >= 'A' && c <= 'Z'); }
int isvowel(char c) {
  return (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u');
}
int N, M, cnt, p[1000005], c[1000005];
bool vis[1000005];
vector<int> g[1000005];
map<pair<int, int>, bool> v;
void DFS(int u, int pr) {
  if (vis[u]) return;
  vis[u] = true;
  for (__typeof(N) i = 1; i <= (N); i++) {
    if (vis[i] && !c[i]) {
      if (v[make_pair(u, i)] && v[make_pair(u, p[u])] &&
          v[make_pair(p[u], p[p[u]])]) {
        c[i] = c[u] = c[p[u]] = 1;
        cnt++;
      } else if (!v[make_pair(u, i)] && !v[make_pair(u, p[u])] &&
                 !v[make_pair(i, p[u])]) {
        c[i] = c[u] = c[p[u]] = 1;
        cnt++;
      }
    } else {
      p[i] = u;
      DFS(i, u);
    }
  }
  return;
}
int main() {
  int i, j, k, l, m, n, t, x, y, z, blank = 0, test = 0;
  scanf("%d %d", &N, &M);
  while (M--) {
    scanf("%d %d", &x, &y);
    v[make_pair(x, y)] = true;
    v[make_pair(y, x)] = true;
  }
  cnt = 0;
  p[1] = 1;
  DFS(1, 1);
  printf("%d\n", cnt);
  return 0;
}
