import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


// !!!Assume bipartite (n vertices overall)!!!
class BMatch {
  int n;
  int[][] g;
  int[] to;
  bool[] vis;
  this(int n) {
    this.n = n; g = new int[][n]; to = new int[n]; vis = new bool[n];
  }
  void ae(int u, int v) {
    g[u] ~= v; g[v] ~= u;
  }
  bool augment(int u) {
    foreach (v; g[u]) if (!vis[v]) {
      vis[v] = true;
      if (to[v] == -1 || augment(to[v])) {
        to[u] = v; to[v] = u; return true;
      }
    }
    return false;
  }
  int solve() {
    int ret;
    to[] = -1;
    foreach (u; 0 .. n) if (to[u] == -1) {
      vis[] = false;
      if (augment(u)) ++ret;
    }
    return ret;
  }
}


void main() {
  try {
    for (; ; ) {
      const N = readInt;
      const M = readInt;
      auto A = new int[M];
      auto B = new int[M];
      foreach (i; 0 .. M) {
        A[i] = readInt - 1;
        B[i] = readInt - 1;
      }
      
      auto deg = new int[N];
      foreach (i; 0 .. M) {
        ++deg[A[i]];
        ++deg[B[i]];
      }
      
      auto bm = new BMatch(N + N);
      foreach (i; 0 .. M) {
        bm.ae(A[i], N + B[i]);
        bm.ae(B[i], N + A[i]);
      }
      int ans = bm.solve;
      debug {
        writeln("ans = ", ans);
      }
      if (ans == N - 1) {
        int um = -1, vm = -1;
        foreach (u; 0 .. N) {
          if (!~bm.to[u]) um = u;
          if (!~bm.to[N + u]) vm = u;
        }
        if (um == vm && deg[um] == 0) {
          --ans;
        }
      }
      debug {
        writeln("ans = ", ans);
      }
      writeln(2 * ans - N);
    }
  } catch (EOFException e) {
  }
}