#ifndef LOCAL
#define FAST_IO
#endif

// ============
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#define OVERRIDE(a, b, c, d, ...) d
#define REP2(i, n) for (i32 i = 0; i < (i32)(n); ++i)
#define REP3(i, m, n) for (i32 i = (i32)(m); i < (i32)(n); ++i)
#define REP(...) OVERRIDE(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define PER(i, n) for (i32 i = (i32)(n) - 1; i >= 0; --i)
#define ALL(x) begin(x), end(x)

using namespace std;

using u32 = unsigned int;
using u64 = unsigned long long;
using i32 = signed int;
using i64 = signed long long;
using f64 = double;
using f80 = long double;

template <typename T>
using Vec = vector<T>;

template <typename T>
bool chmin(T &x, const T &y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T>
bool chmax(T &x, const T &y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}

template <typename T>
Vec<tuple<i32, i32, T>> runlength(const Vec<T> &a) {
    if (a.empty()) {
        return Vec<tuple<i32, i32, T>>();
    }
    Vec<tuple<i32, i32, T>> ret;
    i32 prv = 0;
    REP(i, 1, a.size()) {
        if (a[i - 1] != a[i]) {
            ret.emplace_back(prv, i, a[i - 1]);
            prv = i;
        }
    }
    ret.emplace_back(prv, (i32)a.size(), a.back());
    return ret;
}

#ifdef INT128

using u128 = __uint128_t;
using i128 = __int128_t;

istream &operator>>(istream &is, i128 &x) {
    i64 v;
    is >> v;
    x = v;
    return is;
}
ostream &operator<<(ostream &os, i128 x) {
    os << (i64)x;
    return os;
}
istream &operator>>(istream &is, u128 &x) {
    u64 v;
    is >> v;
    x = v;
    return is;
}
ostream &operator<<(ostream &os, u128 x) {
    os << (u64)x;
    return os;
}

#endif

[[maybe_unused]] constexpr i32 INF = 1000000100;
[[maybe_unused]] constexpr i64 INF64 = 3000000000000000100;
struct SetUpIO {
    SetUpIO() {
#ifdef FAST_IO
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
#endif
        cout << fixed << setprecision(15);
    }
} set_up_io;
// ============

#ifdef DEBUGF
#else
#define DBG(x) (void)0
#endif

// ============

#include <cassert>
#include <queue>
#include <utility>
#include <vector>

std::pair<std::vector<int>, std::vector<int>> hopcroft_karp(int l, int r, const std::vector<std::pair<int, int>> &edges) {
    assert(0 <= l && 0 <= r);
    std::vector<std::vector<int>> g(l);
    for (auto [u, v] : edges) {
        assert(0 <= u && u < l && 0 <= v && v < r);
        g[u].push_back(v);
    }
    std::vector<int> p(l, -1), q(r, -1);
    while (true) {
        std::vector<int> par(l, -1), root(l, -1);
        std::queue<int> que;
        for (int i = 0; i < l; ++i) {
            if (p[i] == -1) {
                que.push(i);
                root[i] = i;
            }
        }
        bool upd = false;
        while (!que.empty()) {
            int v = que.front();
            que.pop();
            if (p[root[v]] != -1) {
                continue;
            }
            for (int u : g[v]) {
                if (q[u] == -1) {
                    while (u != -1) {
                        q[u] = v;
                        std::swap(p[v], u);
                        v = par[v];
                    }
                    upd = true;
                    break;
                }
                int u_ = q[u];
                if (par[u_] == -1) {
                    root[u_] = root[v];
                    par[u_] = v;
                    que.push(u_);
                }
            }
        }
        if (!upd) {
            break;
        }
    }
    return std::make_pair(p, q);
}
// ============

int main() {
    i32 n, m;
    cin >> n >> m;
    Vec<i32> u(m), v(m);
    REP(i, m) {
        cin >> u[i] >> v[i];
        --u[i];
        --v[i];
    }
    Vec<pair<i32, i32>> edges;
    edges.reserve(m);
    REP(i, m) {
        edges.emplace_back(u[i], v[i]);
        edges.emplace_back(v[i], u[i]);
    }
    auto [lm, rm] = hopcroft_karp(n, n, edges);
    i32 ma = n - count(ALL(lm), -1);
    Vec<i32> deg(n, 0);
    REP(i, m) {
        ++deg[u[i]];
        ++deg[v[i]];
    }
    if (ma == n - 1 && count(ALL(deg), 0)) {
        --ma;
    }
    i32 ans = 2 * ma - n;
    cout << ans << '\n';
}