#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef unsigned int uint;
typedef vector<int> vi;
typedef vector< vector <int> > vvi;
typedef pair<int, int> pii;
typedef pair < pair < int, int >, int > piii;
typedef pair < pair <int, int > , pair <int, int> > piiii;
typedef pair<ll, ll> pll;
typedef vector<bool> vb;
typedef vector<char> vc;
typedef vector<string> vs;
 
#define FOR(i,a,b) for(int i = a; i < b; i ++)
#define RFOR(i,a,b) for(int i = a-1; i >= b; i --)
#define all(a) a.begin(), a.end()
#define endl '\n';
#define sz(x) (int)(x).size()
 
#define mp make_pair
#define pb push_back
#define ff first
#define ss second
 
template <typename T>
void pr(vector<T> &v) {
    FOR(i, 0, sz(v)) cout << v[i] << " ";
    cout << endl;
}
template <typename T>
void pr(vector<vector<T> > &v) {
    FOR(i, 0, sz(v)) { pr(v[i]); }
}
template <typename T>
void re(T &x) {
    cin >> x;
}
template <typename T>
void re(vector<T> &a) {
    FOR(i, 0, sz(a)) re(a[i]);
}
template <class Arg, class... Args>
void re(Arg &first, Args &... rest) {
    re(first);
    re(rest...);
}
template <typename T>
void pr(T x) {
    cout << x << endl;
}
template <class Arg, class... Args>
void pr(const Arg &first, const Args &... rest) {
    cout << first << " ";
    pr(rest...);
    cout << endl;
}
void ps() { cout << endl; }
template<class T, class... Ts>
void ps(const T& t, const Ts&... ts) {
    cout << t; if (sizeof...(ts)) cout << " "; ps(ts...);
}
 
const ll MOD  =  998244353;
#define inf 1e18;
#define INF INT_MAX

long double PI = 4*atan(1);
long double eps = 1e-12;


vi adj[3010] = {};
vector<pii> edges;
int n,m; 
vi minlen(3010, 1e8);
vi mincnt(3010, 0);

ll minv = 1e9;
ll minc = 0;

void bfs(int o, int b, vi &d) {
    queue<pii> q;
    d[o] = 0;
    q.push({o,0});

    while(!q.empty()) {
        pii c = q.front(); q.pop();
        int u = c.ff;
        int dd = c.ss;
        for(auto v : adj[u]) {
            if(u == o && v == b) continue;
            if(d[v] == 1e8) {
                d[v] = dd + 1;
                q.push({v, dd+1});
            }
        }
    }
}

void rem(pii e) {
    int o1 = e.ff;
    int o2 = e.ss;

    vi dist1(n, 1e8);
    bfs(o1, o2, dist1);
    vi dist2(n, 1e8);
    bfs(o2, o1, dist2);

    for(int i = 0; i < n; i++) {
        if(i == o1 || i == o2) continue;
        int d = dist1[i] + dist2[i];
        if(d < 1e8) {
            if(d < minv) {
                minv = d;
                minc = 1;
            } else if(d == minv) {
                minc++;
            }
        }
    }


    
}

int main() {
    auto start = chrono::high_resolution_clock::now();
    ios_base::sync_with_stdio(0);cin.tie(0);
    // ofstream cout("disrupt.out");
    // ifstream cin("disrupt.in");
    #ifdef DEBUG
      freopen("input.txt", "r", stdin);
      freopen("output.txt", "w", stdout);
    #endif  

    cin >> n >> m;
    for(int i = 0; i < m; i++) {
        int u,v;
        cin >> u >> v; u--; v--;
        adj[u].pb(v);
        adj[v].pb(u);
        edges.pb({u,v});
    }

    for(auto e : edges) {
        rem(e);
    }

    cout << minc / ((minv - 1) * (minv + 1)) << endl;

    





    
    // auto stop = chrono::high_resolution_clock::now();
    // auto duration = chrono::duration_cast<chrono::microseconds>(stop - start);
    // cout << duration.count() << endl;
    //cin.close();
    //cout.close();
}