#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>

using namespace std;
 
struct UnionFind {
    vector<long long> par;
    vector<long long> siz;

    UnionFind(long long N) : par(N), siz(N) {
        for(long long i = 0; i < N; i++){
            par[i] = i;
            siz[i] = 1;
        }   
    }   
 
    long long root(long long x) {
        if (par[x] == x) return x;
        return par[x] = root(par[x]);
    }   
 
    long long unite(long long x, long long y) {
        long long rx = root(x);
        long long ry = root(y);
        if (rx == ry) return rx; 
        if (siz[rx] > siz[ry]) swap(rx, ry);
        par[rx] = ry; 
        siz[ry] += siz[rx];
        return ry; 
    }   
 
    bool same(long long x, long long y) {
        long long rx = root(x);
        long long ry = root(y);
        return rx == ry; 
    }   
 
    long long size(long long x){ 
        return siz[root(x)];
    }   
};

int main(){
 
    int N, M, mx=0, pu, pv;
    cin >> N >> M;
    vector<int> u(M), v(M);
    for (int i=0; i<M; i++) cin >> u[i] >> v[i];
    UnionFind tree(N+1);
    vector<int> ans(N+1);
 
    for (int i=M-1; i>=0; i--){
        pu = tree.root(u[i]); pv = tree.root(v[i]);
        if (pu == pv) ans[pu]++;
        else{
            tree.unite(pu, pv);
            ans[tree.root(pu)] = max(ans[pu], ans[pv])+1;
        }
    }

    for (int i=1; i<=N; i++) mx = max(mx, ans[i]);

    cout << mx << endl;

    return 0;
}