#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
const int maxn = 100005;
int n,m,s,t;
int head[maxn],ver[maxn << 1],nxt[maxn << 1],cap[maxn << 1],cnt = -1;
queue<int> q;
void add(int u,int v,int t) {
    ver[++ cnt] = v;
    nxt[cnt] = head[u];
    head[u] = cnt;
    cap[cnt] = t;
    return ;
}
int level[maxn],cur[maxn];
bool vis[maxn];
bool bfs(int s,int t) {
    memset(level , 0 , sizeof(level));
    while(!q.empty())q.pop();
    q.push(s);
    level[s] = 1;
    while(!q.empty()) {
        int u = q.front();
        q.pop(); 
        for(int i = head[u];~ i;i = nxt[i]) {
            int v = ver[i];
            if(!level[v]&&cap[i]) {
                level[v] = level[u] + 1;
                q.push(v);
            }
        }
    }
    return level[t] != 0;
}
int dfs(int x,int t,int maxflow) {
    if(x == t||!maxflow)return maxflow;
    int f,flow = 0,rest = maxflow;
    for(int& i = cur[x];~ i;i = nxt[i]) {
        int v = ver[i];
        if(level[v] == level[x] + 1&&(f = dfs(v , t , min(cap[i] , maxflow)))) {
            if(!f) {
                level[v] = 0;
            }      
            flow += f;
            maxflow -= f;
            cap[i] -= f;
            cap[i ^ 1] += f;
            if(!maxflow)break ;
        }
    }
    return flow;
}
int Dinic(int s,int t) {
    int flow = 0;
    while(bfs(s , t)) {
        memcpy(cur , head , sizeof(head));
        flow += dfs(s , t , 0x3f3f3f3f);
    }
    return flow;
}
int main() {
    freopen("tongzhuo.in","r",stdin);
    freopen("tongzhuo.out","w",stdout);
    memset(head , -1 , sizeof(head));
    scanf("%d%d",&n,&m);
    int u,v;
    while(~ scanf("%d%d",&u,&v)) {
        add(u , v , 1);
        add(v , u , 0);
    }
    s = ++ n;
    t = ++ n;
    for(int i = 1;i <= m;++ i) {
        add(s , i , 1);
        add(i , s , 0);
    }
    for(int i = m + 1;i <= n - 2;++ i) {
        add(i , t , 1);
        add(t , i , 0);
    }
    printf("%d\n",Dinic(s , t));
    fclose(stdin);
    fclose(stdout);
    return 0;
}