1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
#include <bits/stdc++.h>
using namespace std;
#define PII pair<int, int>
#define VI vector<int>
#define VPII vector<PII>
#define LL long long
#define LD long double
#define f first
#define s second
#define MP make_pair
#define PB push_back
#define endl '\n'      // UWAGA
#define ALL(c) (c).begin(), (c).end()
#define SIZ(c) (int)(c).size()
#define REP(i, n) for(int i = 0; i < (int)(n); ++i)
#define FOR(i, b, e) for(int i = (b); i <= (int)(e); ++i)
#define FORD(i, b, e) for(int i = (b); i >= (int)(e); --i)
#define random_shuffle(V) shuffle(V, rng)

#define sim template<class n
sim, class s> ostream & operator << (ostream &p, pair<n, s> x)
{return p << "<" << x.f << ", " << x.s << ">";}
sim> auto operator << (ostream &p, n y) ->
typename enable_if<!is_same<n, string>::value, decltype(y.begin(), p)>::type 
{int o = 0; p << "{"; for(auto c: y) {if(o++) p << ", "; p << c;} return p << "}";}
void dor() {cerr << endl;}
sim, class...s> void dor(n p, s...y) {cerr << p << " "; dor(y...);}
sim, class s> void mini(n &p, s y) {if(p>y) p = y;}
sim, class s> void maxi(n &p, s y) {if(p<y) p = y;}
#ifdef DEB
#define debug(...) dor(__FUNCTION__, ":", __LINE__, ": ", __VA_ARGS__)
#else
#define debug(...)
#endif 

#define I(x) #x " =", (x), " "
#define A(a, i) #a "[" #i " =", i, "] =", a[i], " "

mt19937 rng((unsigned int)chrono::steady_clock::now().time_since_epoch().count());
int R(int a, int b) {return (int)(rng()%(b-a+1)) + a;}
// #pragma GCC optimize("Ofast")
// while (clock()<=69*CLOCKS_PER_SEC)

const int MXN = 5e5+6;
VPII V[MXN];
int REMOVED1;
int REMOVED2;
int stan[MXN];
int dep[MXN];
int low[MXN];
LL res = 0;
int n, m;

int cnt = 0;
void dfs2(int v)
  {
  if(stan[v])return;
  cnt++;
  stan[v] = 1;
  for(auto i: V[v])
    if(i.s != REMOVED1 && i.s != REMOVED2)
      dfs2(i.f);
  }


void dfs(int v, int pop, int de)
  {
  low[v] = dep[v] = de;
  stan[v] = 1;
  for(auto i: V[v])
    {
    if(i.s == REMOVED1 || i.s == REMOVED2)continue;
    if(i.s == pop)continue;
    if(stan[i.f] == 1)
      {
      mini(low[v], dep[i.f]);
      }
    else
      {
      if(stan[i.f] == 2)continue;
      dfs(i.f, i.s, de+1);
      mini(low[v], low[i.f]);
      }
    }

  if(v != 1 && low[v] == dep[v])
    {
    // debug(REMOVED1, REMOVED2, pop);
    if(pop > REMOVED2)res++;
    }
  stan[v] = 2;
  }

int main()
  {
  ios_base::sync_with_stdio(0);

  cin >> n >> m;
  REP(i, m)
    {
    int a, b;
    cin >> a >> b;
    V[a].PB(MP(b, i));
    V[b].PB(MP(a, i));
    }

  REP(i, m)
    {
    FOR(j, i+1, m-1)
      {
      REMOVED1 = i;
      REMOVED2 = j;

      FOR(u, 1, n)stan[u] = 0;
      cnt = 0;
      dfs2(1);
      if(cnt != n)
        {
        // debug(REMOVED1, REMOVED2);
        res += m - REMOVED2 - 1;
        continue;
        }

      FOR(u, 1, n)stan[u] = 0;
      dfs(1, -1, 1);
      }
    }
  cout << res << endl;
}