#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
#include <set>
#include <stack>
#include <queue>
#include <cmath>
#include <iomanip>
#include <numeric>
#include <string>
#include <bitset>
#include <assert.h>

// #define _GLIBCXX_DEBUG
// #define _LIBCPP_DEBUG 0
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define revrep(i, n) for(int i = (int)(n -1); i >= 0; --i)
#define range(i, s, t) for (int i = (int)(s); i < (int)(t); ++i)
#define revrange(i, s, t) for(int i = (int)(t - 1); i >= (int)(s); --i)
#define srange(i, s, t, step) for(int i = (int)(s); i < (int)(t); i+=int(step))
#define popcnt(x) __builtin_popcountll(x)

using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
template<class T> inline bool chmax(T& a, T b){ if (a < b){ a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b){ if (a > b){ a = b; return true; } return false; }
inline bool inside(int x, int y, int h, int w) { return (x >= 0 && x < h && y >= 0 && y < w); }
int dx[] = {0, -1, 0, 1};
int dy[] = {-1, 0, 1, 0};


struct union_find{
  public:
    union_find(int size): _n(size), root(size, -1) {}

    int find(int x){
        if (root[x] < 0) return x;
        root[x] = find(root[x]);
        return root[x];
    }
    bool same(int x, int y){
        return find(x) == find(y);
    }
    bool merge(int x, int y){
        x = find(x); y = find(y);
        if (x == y) return false;
        if (-root[x] < -root[y]) swap(x, y);
        root[x] += root[y];
        root[y] = x;
        return true;
    }
    int size(int x){
        return -root[x];
    }
  private:
    int _n;
    vector<int> root;
};


int main() {
    int n, m;
    cin >> n >> m;
    vector<int> a(m), b(m);
    rep(i, m) {
        cin >> a[i] >> b[i];
        a[i]--;
        b[i]--;
    }

    union_find uf(n);
    vector<int> cnt(n, 0);
    revrep(i, m) {
        int p = uf.find(a[i]);
        int q = uf.find(b[i]);
        int x = max(cnt[p], cnt[q]);
        uf.merge(p, q);
        cnt[uf.find(p)] = x + 1;
    }

    int ans = 0;
    rep(i, n) chmax(ans, cnt[i]);
    cout << ans << endl;
    return 0;
}