#include <bits/stdc++.h>
using namespace std;

struct dsu {
  public:
    vector<int> cnt;
    dsu() : _n(0) {}
    dsu(int n) : _n(n), parent_or_size(n, -1), cnt(n) {}

    int merge(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        int x = leader(a), y = leader(b);
        if (x == y) return x;
        if (-parent_or_size[x] < -parent_or_size[y]) std::swap(x, y);
        parent_or_size[x] += parent_or_size[y];
        cnt[x] = max(cnt[x], cnt[y]) + 1;
        parent_or_size[y] = x;
        return x;
    }

    bool same(int a, int b) {
        assert(0 <= a && a < _n);
        assert(0 <= b && b < _n);
        return leader(a) == leader(b);
    }

    int leader(int a) {
        assert(0 <= a && a < _n);
        if (parent_or_size[a] < 0) return a;
        return parent_or_size[a] = leader(parent_or_size[a]);
    }

    int size(int a) {
        assert(0 <= a && a < _n);
        return -parent_or_size[leader(a)];
    }

    std::vector<std::vector<int>> groups() {
        std::vector<int> leader_buf(_n), group_size(_n);
        for (int i = 0; i < _n; i++) {
            leader_buf[i] = leader(i);
            group_size[leader_buf[i]]++;
        }
        std::vector<std::vector<int>> result(_n);
        for (int i = 0; i < _n; i++) {
            result[i].reserve(group_size[i]);
        }
        for (int i = 0; i < _n; i++) {
            result[leader_buf[i]].push_back(i);
        }
        result.erase(
            std::remove_if(result.begin(), result.end(),
                           [&](const std::vector<int>& v) { return v.empty(); }),
            result.end());
        return result;
    }

  private:
    int _n;
    // root node: -1 * component size
    // otherwise: parent
    std::vector<int> parent_or_size;
};

int main(){
    int n, m, u, v;
    cin >> n >> m;
    vector<pair<int,int>> edge(m);
    for(int i = 0; i < m; i++){
        cin >> u >> v;
        edge[i] = {--u, --v};
    }
    reverse(edge.begin(), edge.end());
    int ans = 0;
    dsu uf(n);
    for(int i = 0; i < m; i++){
        tie(u, v) = edge[i];
        u = uf.leader(u), v = uf.leader(v);
        if(uf.same(u, v)){
            uf.cnt[u]++;
            ans = max(ans, uf.cnt[u]);
        }else{
            ans = max(ans, max(uf.cnt[u], uf.cnt[v]) + 1);
            uf.merge(u, v);
        }
    }
    cout << ans << '\n';
}