#include<fstream>
#include<vector>
using namespace std;
ifstream f("biconex.in");
ofstream g("biconex.out");
int n,m,x,y,i,j,det[100005],con,fin;
vector<int>v[100005];
bool viz[100005],ok;
void dfs(int nod,bool val)
{
    if(val==0)
      viz[nod]=1;
    else
      viz[nod]=0;
    for(int i=0;i<v[nod].size();i++)
      if(viz[v[nod][i]]==val)
        dfs(v[nod][i],val);
}
int main()
{
    f>>n>>m;
    for(i=1;i<=m;i++)
    {
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for(i=1;i<=n;i++)
    {
        if(ok==0)
          viz[i]=1;
        else
          viz[i]=0;
        con=0;
        for(j=0;j<v[i].size();j++)
          if(viz[v[i][j]]==ok)
          {
              con++;
              dfs(v[i][j],ok);
          }
        det[i]=con;
        if(ok==0)
          ok=1;
        else
          ok=0;
    }
    bool ok=0;
    for(i=1;i<=n;i++)
      if(det[i]>1)
        if(ok==0)
        {
            fin+=det[i];
            ok=1;
        }
        else
          fin+=det[i]-1;
    g<<fin;
    return 0;
}