#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < int(n); i++)
#define per(i, n) for (int i = (n)-1; 0 <= i; i--)
#define rep2(i, l, r) for (int i = (l); i < int(r); i++)
#define per2(i, l, r) for (int i = (r)-1; int(l) <= i; i--)
#define each(e, v) for (auto& e : v)
#define MM << " " <<
#define pb push_back
#define eb emplace_back
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define sz(x) (int)x.size()
template <typename T> void print(const vector<T>& v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << (i == n - 1 ? '\n' : ' ');
    if (v.empty()) cout << '\n';
}
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <typename T> bool chmax(T& x, const T& y) {
    return (x < y) ? (x = y, true) : false;
}
template <typename T> bool chmin(T& x, const T& y) {
    return (x > y) ? (x = y, true) : false;
}
template <class T>
using minheap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
template <class T> using maxheap = std::priority_queue<T>;
template <typename T> int lb(const vector<T>& v, T x) {
    return lower_bound(begin(v), end(v), x) - begin(v);
}
template <typename T> int ub(const vector<T>& v, T x) {
    return upper_bound(begin(v), end(v), x) - begin(v);
}
template <typename T> void rearrange(vector<T>& v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
}

// __int128_t gcd(__int128_t a, __int128_t b) {
//     if (a == 0)
//         return b;
//     if (b == 0)
//         return a;
//     __int128_t cnt = a % b;
//     while (cnt != 0) {
//         a = b;
//         b = cnt;
//         cnt = a % b;
//     }
//     return b;
// }

long long extGCD(long long a, long long b, long long& x, long long& y) {
    if (b == 0) {
        x = 1;
        y = 0;
        return a;
    }
    long long d = extGCD(b, a % b, y, x);
    y -= a / b * x;
    return d;
}

struct UnionFind {
    vector<int> data;
    int num;

    UnionFind(int sz) {
        data.assign(sz, -1);
        num = sz;
    }

    bool unite(int x, int y) {
        x = find(x), y = find(y);
        if (x == y) return (false);
        if (data[x] > data[y]) swap(x, y);
        data[x] += data[y];
        data[y] = x;
        num--;
        return (true);
    }

    int find(int k) {
        if (data[k] < 0) return (k);
        return (data[k] = find(data[k]));
    }

    int size(int k) { return (-data[find(k)]); }

    bool same(int x, int y) { return find(x) == find(y); }

    int operator[](int k) { return find(k); }
};

template <int mod> struct Mod_Int {
    int x;

    Mod_Int() : x(0) {}

    Mod_Int(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

    static int get_mod() { return mod; }

    Mod_Int& operator+=(const Mod_Int& p) {
        if ((x += p.x) >= mod) x -= mod;
        return *this;
    }

    Mod_Int& operator-=(const Mod_Int& p) {
        if ((x += mod - p.x) >= mod) x -= mod;
        return *this;
    }

    Mod_Int& operator*=(const Mod_Int& p) {
        x = (int)(1LL * x * p.x % mod);
        return *this;
    }

    Mod_Int& operator/=(const Mod_Int& p) {
        *this *= p.inverse();
        return *this;
    }

    Mod_Int& operator++() { return *this += Mod_Int(1); }

    Mod_Int operator++(int) {
        Mod_Int tmp = *this;
        ++*this;
        return tmp;
    }

    Mod_Int& operator--() { return *this -= Mod_Int(1); }

    Mod_Int operator--(int) {
        Mod_Int tmp = *this;
        --*this;
        return tmp;
    }

    Mod_Int operator-() const { return Mod_Int(-x); }

    Mod_Int operator+(const Mod_Int& p) const { return Mod_Int(*this) += p; }

    Mod_Int operator-(const Mod_Int& p) const { return Mod_Int(*this) -= p; }

    Mod_Int operator*(const Mod_Int& p) const { return Mod_Int(*this) *= p; }

    Mod_Int operator/(const Mod_Int& p) const { return Mod_Int(*this) /= p; }

    bool operator==(const Mod_Int& p) const { return x == p.x; }

    bool operator!=(const Mod_Int& p) const { return x != p.x; }

    Mod_Int inverse() const {
        assert(*this != Mod_Int(0));
        return pow(mod - 2);
    }

    Mod_Int pow(long long k) const {
        Mod_Int now = *this, ret = 1;
        for (; k > 0; k >>= 1, now *= now) {
            if (k & 1) ret *= now;
        }
        return ret;
    }

    friend ostream& operator<<(ostream& os, const Mod_Int& p) {
        return os << p.x;
    }

    friend istream& operator>>(istream& is, Mod_Int& p) {
        long long a;
        is >> a;
        p = Mod_Int<mod>(a);
        return is;
    }
};

ll mpow2(ll x, ll n, ll mod) {
    ll ans = 1;
    x %= mod;
    while (n != 0) {
        if (n & 1) ans = ans * x % mod;
        x = x * x % mod;
        n = n >> 1;
    }
    ans %= mod;
    return ans;
}

template <typename T> T modinv(T a, const T& m) {
    T b = m, u = 1, v = 0;
    while (b > 0) {
        T t = a / b;
        swap(a -= t * b, b);
        swap(u -= t * v, v);
    }
    return u >= 0 ? u % m : (m - (-u) % m) % m;
}

ll divide_int(ll a, ll b) {
    if (b < 0) a = -a, b = -b;
    return (a >= 0 ? a / b : (a - b + 1) / b);
}

// const int MOD = 1000000007;
const int MOD = 998244353;
using mint = Mod_Int<MOD>;

mint mpow(mint x, ll n) {
    bool rev = n < 0;
    n = abs(n);
    mint ans = 1;
    while (n != 0) {
        if (n & 1) ans *= x;
        x *= x;
        n = n >> 1;
    }
    return (rev ? ans.inverse() : ans);
}

// ----- library -------
template <typename F> // 流量の型
struct Dinic {
    struct edge {
        int to;
        F cap;
        int rev;
        edge(int to, F cap, int rev) : to(to), cap(cap), rev(rev) {}
    };

    vector<vector<edge>> es;
    vector<int> d, pos;
    const F zero_F, INF_F;
    const int n;

    Dinic(int n, F zero_F = 0, F INF_F = numeric_limits<F>::max() / 2) : es(n), d(n), pos(n), zero_F(zero_F), INF_F(INF_F), n(n) {}

    void add_edge(int from, int to, F cap, bool directed = true) {
        es[from].emplace_back(to, cap, (int)es[to].size());
        es[to].emplace_back(from, directed ? zero_F : cap, (int)es[from].size() - 1);
    }

    bool _bfs(int s, int t) {
        fill(begin(d), end(d), -1);
        queue<int> que;
        d[s] = 0;
        que.push(s);
        while (!que.empty()) {
            int i = que.front();
            que.pop();
            for (auto &e : es[i]) {
                if (e.cap > zero_F && d[e.to] == -1) {
                    d[e.to] = d[i] + 1;
                    que.push(e.to);
                }
            }
        }
        return d[t] != -1;
    }

    F _dfs(int now, int t, F flow) {
        if (now == t) return flow;
        for (int &i = pos[now]; i < (int)es[now].size(); i++) {
            edge &e = es[now][i];
            if (e.cap > zero_F && d[e.to] > d[now]) {
                F f = _dfs(e.to, t, min(flow, e.cap));
                if (f > zero_F) {
                    e.cap -= f;
                    es[e.to][e.rev].cap += f;
                    return f;
                }
            }
        }
        return zero_F;
    }

    F max_flow(int s, int t) { // 操作後の d 配列は最小カットの 1 つを表す（0 以上なら s 側、-1 なら t 側）
        F flow = zero_F;
        while (_bfs(s, t)) {
            fill(begin(pos), end(pos), 0);
            F f = zero_F;
            while ((f = _dfs(s, t, INF_F)) > zero_F) flow += f;
        }
        return flow;
    }
};
// ----- library -------

int main() {
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    cout << fixed << setprecision(15);

    int n, m;
    cin >> n >> m;
    Dinic<int> mf(n * 4 + 2);
    int u, v;
    vector<int> d(n, 0);
    rep(i, m) {
        cin >> u >> v, u--, v--;
        d[u]++, d[v]++;
        rep(s, 2) mf.add_edge(u * 2 + s, v * 2 + n * 2 + (s ^ 1), 1);
    }
    rep(i, n * 2) mf.add_edge(n * 4, i, 1), mf.add_edge(i + n * 2, n * 4 + 1, 1);
    int c0 = 0;
    rep(i, n) if (d[i] == 0) c0++;
    int ans = mf.max_flow(n * 4, n * 4 + 1) * 2 - n;
    if (c0 == 1)
        chmin(ans, n - 4);
    cout << ans << endl;
}