#include <cstdio>
#include <cstring>
#include <climits>
#include <queue>
#include <algorithm>
const int MAX_N = 10000;
const int MAX_M = 1000000;
struct Node;
struct Edge;
struct Node {
    Edge *e;
    int pos, label;
    bool vis;
    Node() : e(NULL), pos(-1), label(0), vis(false) {}
} N[MAX_N + 1];
struct Edge {
    Node *fr, *to;
    Edge *ne;
    Edge(Node *fr, Node *to) : fr(fr), to(to), ne(fr->e) {}
};
inline void addEdge(int fr, int to) {
    N[fr].e = new Edge(&N[fr], &N[to]);
    N[to].e = new Edge(&N[to], &N[fr]);
}
std::priority_queue< std::pair<int, Node *> > q;
int n, m;
inline int mcs() {
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        q.push(std::make_pair(0, &N[i]));
    }
    for (int i = n; i >= 1; i--) {
#ifdef DBG
        Node *u = q.top().second;
#endif
        while (q.top().second->vis) q.pop();
        Node *v = q.top().second;
        v->pos = i;
        v->vis = true;
        for (Edge *e = v->e; e; e = e->ne) {
            if (!e->to->vis) {
                q.push(std::make_pair(++e->to->label, e->to));
            }
        }
    }
    for (int i = 1; i <= n; i++) {
        int sum = 0;
        for (Edge *e = N[i].e; e; e = e->ne) {
            if (e->to->pos > N[i].pos) sum++;
        }
        ans = std::max(ans, sum + 1);
    }
    return ans;
}
int main() {
    scanf("%d %d", &n, &m);
    for (int i = 1; i <= m; i++) {
        int u, v;
        scanf("%d %d", &u, &v);
        addEdge(u, v);
    }
    printf("%d\n", mcs());
    return 0;
}