#include<bits/stdc++.h>
#define pow power
#define ll long long
#define ull unsigned long long
using namespace std;
template<typename T>void read(T &x)
{
    x=0;int f=1;
    char c=getchar();
    for(;!isdigit(c);c=getchar()) if(c=='-') f=-1;
    for(;isdigit(c);c=getchar()) x=(x<<3)+(x<<1)+c-'0';
    x=x*f;
}
template<typename T>inline void write(T x)
{
    if(x==0)
    {
        putchar('0');
        return;
    }
    int len=0;
    short c[55];
    if(x<0) x=-x,putchar('-');
    while(x) c[len++]=x%10+'0',x/=10;
    while(len--) putchar(c[len]);
}
template<typename T>void writeln(T x)
{
    write(x);
    putchar('\n');
}
template<typename T>void writesp(T x)
{
    write(x);
    putchar(' ');
}
const int N=5005;
int id,T,n,m,s,t,cnt,head[N<<1];
struct qwq{int v,nxt,c;}edge[N<<3];
void add(int x,int y,int c){
    edge[++cnt]=(qwq){y,head[x],c};
    head[x]=cnt;
}
queue<int>q;
int dep[N<<1],du[N];
bool bfs(){
    while(!q.empty()) q.pop();
    for(int i=0;i<=2*n+1;i++) dep[i]=0;
    q.push(s); dep[s]=1;
    while(!q.empty()){
        int u=q.front(); q.pop();
        for(int i=head[u];i;i=edge[i].nxt){
            int v=edge[i].v,c=edge[i].c;
            if(dep[v]||!c) continue;
            dep[v]=dep[u]+1;
            if(v==t) return 1;
            q.push(v);
        }
    }
    return 0;
}
int dfs(int u,int flow){
    if(u==t) return flow;
    int rest=flow;
    for(int i=head[u];i;i=edge[i].nxt){
        int v=edge[i].v,c=edge[i].c;
        if(dep[v]==dep[u]+1&&c){
            int nwfl=dfs(v,min(rest,c));
            if(!nwfl) dep[v]=0;
            edge[i].c-=nwfl;
            edge[i^1].c+=nwfl;       
            rest-=nwfl;
            if(!rest) break;    
        }
    }
    return flow-rest;
}
int main()
{
    // freopen("aka.in","r",stdin);
    // freopen("aka.out","w",stdout);
    // read(id); read(T);
    T=1;
    while(T--){
        read(n); read(m);
        cnt=1;
        int gu=0;
        memset(head,0,sizeof(head));
        memset(du,0,sizeof(du));
        for(int i=1;i<=n;i++){
            add(0,i,1);
            add(i,0,0);
            add(i+n,2*n+1,1);
            add(2*n+1,i+n,0);
        }
        for(int i=1;i<=m;i++){
            int u,v;
            read(u),read(v);
            du[u]++,du[v]++;
            add(u,v+n,1);
            add(v+n,u,0);
            add(v,u+n,1);
            add(u+n,v,0);
        }
        for(int i=1;i<=n;i++){
            if(!du[i]) gu++;
        }
        s=0,t=2*n+1;
        int flow=0;
        while(bfs()) flow+=dfs(s,(1<<30));
        if(flow==n-1&&gu==1) flow--;
        cout<<flow*2-n<<endl;
    }
    return 0;
}